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Lenz, Lucia [Verfasser], and Hermann [Akademischer Betreuer] Grabert. "Spin orbit interactions in carbon based materials = Spin-Orbit Wechselwirkungen in Kohlenstoff basierten Materialien." Freiburg : Universität, 2013. http://d-nb.info/1123478147/34.
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Stano, Peter. "Controlling electron quantum dot qubits by spin-orbit interactions." [S.l.] : [s.n.], 2007. http://deposit.ddb.de/cgi-bin/dokserv?idn=983802254.
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Smirnov, Sergey. "Ratchet phenomena in quantum dissipative systems with spin-orbit interactions." kostenfrei, 2009. http://www.opus-bayern.de/uni-regensburg/volltexte/2009/1407/.
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Pham, Thaï Ha. "Spin-Orbit effect in ferrimagnetic thin film." Electronic Thesis or Diss., Université de Lorraine, 2020. http://www.theses.fr/2020LORR0051.
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Un fort intérêt se porte actuellement sur l'influence du couplage spin-orbite sur les propriétés de transport. Notamment la possibilité de retourner l’aimantation grâce au couple spin-orbite (SOT). Afin d’envisager l’utilisation du SOT pour des applications dans le domaine de l’électronique de spin il est nécessaire de réduire le courant critique nécessaire au retournement et diminuer ou éliminer le champ magnétique externe planaire appliqué. Mon travail de thèse concerne l’étude expérimentale de systèmes bicouches métaux lourds/ ferrimagnétique (W/ CoxTb1−x ou Pt / CoxTb1−x ). Dans les alliages ferrimagnétiques, l’aimantation du sous réseau du Cobalt est couplé antiparallèlement à l’aimantation du sous réseau de Terbium. Ces alliages sont particulièrement intéressants car pour une certaine concentration, il existe une température pour laquelle l’aimantation des deux sous réseaux sont égales et donc que l’aimantation résultante est nulle. Dans un premier temps j’ai caractérisé ces systèmes par magnétométrie et par mesures de résistance Hall anomale pour des températures allant de 10 à 350 K. Les expériences de renversement d’aimantation induite par le courant ont été effectuées dans une géométrie « couple Spin-orbite » (SOT) où les impulsions de courant sont injectées dans le plan et le retournement de l’aimantation est détectée par la mesure de la résistance de Hall. Le retournement complet de l'aimantation a été observée dans tous les échantillons. Le courant de retournement varie de façon continue avec la composition de l’alliage et nous n’avons pas observé une réduction de celui-ci au point de compensation malgré la forte augmentation de l’efficacité du SOT. Un modèle basé sur les équations de Landau-Lifschitz-Gilbert couplées montre que la densité du courant de retournement est proportionnelle à l’anisotropie perpendiculaire effective, qui ne diminue pas au point de compensation. Bien que le TbCo possède une forte anisotropie magnétique perpendiculaire, le retournement se produit pour un champ magnétique planaire faible. Nous avons pu montrer que le chauffage provoqué par le courant joue un rôle important. En effet le retournement semble se produire à une température de commutation caractéristique Tswitch induite par le chauffage Joule qui est supérieure aux températures de compensation magnétique et angulaire mais inférieure à sa température de Curie (TC). Tout se passe comme s’il fallait atteindre une température proche de TC pour que le retournement ait lieuThe influence of spin-orbit coupling on transport properties has been a topic of strong and growing interest in the last ten years. In order to use of spin-orbit torque for applications in the field of spin electronics, it is necessary to reduce the critical current necessary for the reversal and to decrease or eliminate the planar external magnetic field applied. My thesis work concerns the experimental study of heavy metal / ferrimagnetic bilayer model systems (W / CoxTb1-x or Pt / CoxTb1 - x). In such ferrimagnetic alloys, the magnetization of the Cobalt sub-lattice is coupled antiparallel to the magnetization of the Terbium sub-lattice. These alloys are particularly interesting because for certain concentration, there is a temperature for which the magnetization of the two sub-networks are equal resulting in zero magnetization. This is the magnetization compensation temperature. At first I characterized these systems using magnetometry and Hall cross measurements for temperatures ranging from 10 to 350 K. The experiments of magnetization reversal of magnetization induced by the current were carried out in a "Spin- orbit torque” (SOT) geometry where the current pulses are injected into the plane and the reversal of the magnetization is detected by measuring the Hall resistance. The complete magnetization reversal was observed in all the samples. The current reversal was found to vary continuously with the alloy composition and we did not observe any reduction at the compensation point despite the large increase in the SOT efficiency. A model based on the coupled Landau-Lifschitz-Gilbert equations shows that the reversal current density is proportional to the effective perpendicular anisotropy, which does not decrease at the compensation point. Although TbCo has a strong perpendicular magnetic anisotropy, the reversal occurs for a weak planar magnetic field. We were able to show that the heating caused by the current plays an important role in the switching. Indeed the reversal seems to occur at a characteristic switching temperature (Tswitch) induced by Joule heating. Tswitch is larger than the magnetic and angular compensation temperatures, but lower than the Curie temperature. Everything happens as if it was necessary to reach a temperature close to the order temperature for the reversal to take place
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Hernangomez, Perez Daniel. "Spin-orbit Coupling and Strong Interactions in the Quantum Hall Regime." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENY087.
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L'effet Hall quantique, qui apparaît dans les gaz d'électrons bidimensionnels soumis à un champ magnétique perpendiculaire et à basses températures, a été un sujet de recherche intense pendant les derniers trente ans, en particulier, à cause des manifestations spectaculaires de la mécanique quantique dans les propriétés de transport à l'échelle macroscopique. Dans cette thèse, on étend l'horizon de la recherche au niveau théorique sur ce sujet en considérant les effets du couplage spin-orbite et l'interaction électron-électron de façon analytique dans ce régime.Dans la première partie de ce manuscrit, on considère l'effet simultané du couplage spin-orbite de type Rashba et l'interaction Zeeman dans le régime de l'effet Hall quantique entier. Pour cela, on étend un formalisme de fonctions de Green basé sur des états de vortex cohérents avec l'objectif d'inclure le couplage entre les degrés de liberté orbitaux et de spin dans les états de dérive électroniques. Puis, comme première application, on montre comment obtenir analytiquement, nonperturbativement et de manière contrôlée des fonctionnelles quantiques (spectre et densité d'états locale) pour des potentiels électrostatiques arbitraires et localement plats. Les fonctionnelles sont ensuite analysées dans différents régimes de températures et comparées aux données expérimentales obtenues à partir des sondes de spectroscopie locales. Comme seconde mise en pratique du formalisme, on étudie en profondeur les propriétés de transport de charge et de spin dans un régime hydrodynamique d'équilibre local (ou quasi-équilibre) et dérive des expressions analytiques qui incorporent les caractères non-relativiste et relativiste des gaz d'électrons avec couplage spin-orbite de type Rashba.Dans la deuxième partie de cette thèse, on s'occupe du problème de traiter analytiquement les fortes interactions électron-électron dans le régime de l'effet Hall quantique fractionnaire. A cette fin, on étudie un problème à deux corps généralisé avec du désordre et des corrélations électroniques, en utilisant une nouvelle représentation d'états de vortex cohérents. Des corrélations à longue portée entre les particules sont incorporées de manière topologique à travers la présence d'une métrique non-Euclidienne. Subséquemment, on montre que ces états de vortex forment bien une base d'un espace de Hilbert élargi, puis on dérive l'équation du mouvement pour la fonction de Green. Enfin, on vérifie la consistance de notre théorie pour tout niveau de Landau de paire et on discute la nécessité d'aller au-delà de la limite semiclassique (à champ magnétique infinie) pour obtenir des gaps dans chaque niveau de énergieThe quantum Hall effect, appearing in disordered two-dimensional electron gases under strong perpendicular magnetic fields and low temperatures, has been a subject of intense research during the last thirty years due to its very spectacular macroscopic quantum transport properties. In this thesis, we expand the theoretical horizon by analytically considering the effects of spin-orbit coupling and strong electron-electron interaction in these systems.In the first part of the manuscript, we examine the simultaneous effect of Rashba spin-orbit and Zeeman interaction in the integer quantum Hall regime. Under these conditions, we extend a coherent-state vortex Green's function formalism to take into account the coupling between orbital and spin degrees of freedom within the electronic drift states. As a first application of this framework, we analytically compute controlled microscopic nonperturbative quantum functionals, such as the energy spectrum and the local density of states, in arbitrary locally flat electrostatic potential landscapes, which are then analyzed in detail in different temperature regimes and compared to scanning tunnelling experimental data. As a second application, we thoroughly study local equilibrium charge and spin transport properties and derive analytical useful formulas which incorporate the mixed non-relativistic and relativistic character of Rashba-coupled electron gases.In the second part of this thesis, we deal with the problem of analytically incorporating strong electron-electron interactions in the fractional quantum Hall regime. To this purpose, we consider a generalized two-body problem where both disorder and correlations are combined and introduce a new vortex coherent-state representation of the two-body states that naturally include long-range correlations between the electrons. The novelty of this theory is that correlations are topologically built in through the non-Euclidean metric of the Hilbert space. Next, we show that this kind of vortex states form a basis of an enlarged Hilbert space and derive the equation of motion for the Green's function in this representation. Finally, we check the consistency of our approach for any Landau level of the pair and discuss the necessity of going beyond the semiclassical (infinite magnetic field) approximation to obtain energy gaps within each energy level
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Bush, Matthew Peter. "Spin-dependent interactions in the three-body eikonal model." Thesis, University of Surrey, 1997. http://epubs.surrey.ac.uk/844619/.
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A derivation of the elastic scattering differential cross section, within a three-body eikonal model, that treats both central and spin-orbit interactions between the constituent projectile clusters and the target is presented. This formalism is then used in the theoretical study of the scattering of 8B from 12C at 40 MeV/nucleon. The proton halo candidate, 8B, is taken to consist of a single valence proton orbiting a 7Be core cluster. Calculation of the elastic scattering amplitude relies upon determining the phase shifts caused as the projectile passes through the region of interaction with the target. A form for the orbital angular momentum operator of each projectile cluster about the target is obtained that allows a relatively simple form for the spin-orbit phase shift functions, analogous to those for the central interactions, to be deduced. The study of the angular distribution of the elastic scattering differential cross section is carried out in two parts. Initially the effect of elastic break-up and recombination of the projectile during the scattering process, only taking into account central interactions, is studied. To gauge the magnitude of these effects, within the three-body model, the elastic scattering differential cross section, in the limit of no projectile break-up, is derived. Despite the very small binding energy of 8B it is shown that these effects are quite small. It is also shown, however, that these effects become more conspicuous as the valence proton becomes less localised about the core. Finally the effect of including spin-orbit interactions is studied. In the system under study these effects are shown to have an almost negligible effect on the angular distribution of the differential cross section. However, increasing the projectile kinetic energy to the region of hundreds of MeV/nucleon is seen to increase their significance. Future calculations hope to look at the angular distribution of the elastic scattering differential cross section and vector and tensor analysing powers of polarised beams of deuterons as these systems are expected to show more sensitivity to spin- orbit interactions. Furthermore, with the possibility of polarised beams of halo nuclei, the three-body Glauber model would be an ideal theoretical tool with which to study certain of their spin-related phenomena too.
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Sichau, Jonas [Verfasser], and Robert H. [Akademischer Betreuer] Blick. "Electron Spin Resonance Studies on Spin-Orbit Interactions in Graphene / Jonas Sichau ; Betreuer: Robert H. Blick." Hamburg : Staats- und Universitätsbibliothek Hamburg, 2019. http://d-nb.info/1198404183/34.
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Kato, Takashi, Yasuhito Ishikawa, Hiroyoshi Itoh, and Jun-ichiro Inoue. "Intrinsic anisotropic magnetoresistance in spin-polarized two-dimensional electron gas with Rashba spin-orbit interaction." American Physical Society, 2008. http://hdl.handle.net/2237/11252.
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Liu, Jia, and 刘佳. "Exact solutions for electron pairing models with spin-orbit interactions and Zeeman coupling." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2013. http://hdl.handle.net/10722/196010.
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Although a number of methods with appropriate approximations, such as mean-field theory, local density approximation, and tight-binding method have been well developed and widely used in solid state physics, they possess strong limitations, and thus physicists never stop trying to find methods that could rigorously solve the models of condensed matter systems. This thesis presents several new exact solutions for electron pairing models with spin-orbit interactions and Zeeman coupling, which have not been studied before.
First, a type of electron pairing model with spin-orbit interactions or Zeeman coupling is solved exactly in the framework of the Richardson’s previous work for 2D cases. Based on the exact solutions for the electron pairing model with spin-orbit interactions, it is shown rigorously that the pairing symmetry is of the p+ip wave and the ground state possesses time-reversal symmetry, which are expected by the meanfield theory. And the difference is that such peroration from our framework is valid for any strength of the pairing interactions. Intriguingly, how Majorana fermions can emerge is also elaborated in a ribbon system as well. Condensation energy and critical magnetic field are calculated in two systems with the exact solutions, and compared with the relevant results achieved by the mean-field theory, the differences between our results and the mean-field theory show the significance of the work for exact solutions.
Secondly, we generalize our scenario to 3D cases. Several remarks of the 3D case are given following the significant results from the 2D cases. And an unconventional type of Fulde-Ferrel-Larkin-Ovchinnikov ground state is revealed exactly, in which the center-of-mass momentum of the fermion pair is proportional to the Zeeman field. As a by-product, a similar Fulde-Ferrel-Larkin-Ovchinnikov state is also disclosed when the magnetic field is in the same plane of k for 2D case. In addition, applying the transformative Richardson ansatz in bosonic system, we elaborate on the drifting effect of the Zeeman field on the spin-orbit-coupled Bose-Einstein condensed matter as well.
Finally, we discuss the application of the exact solutions in quantum entanglement quantification. The entanglement monotone concurrence is calculated with exact solutions for two models. It is found to be a smooth function of pairing interactions, as expected.published_or_final_version
Physics
Doctoral
Doctor of Philosophy
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Katukuri, Vamshi Mohan. "Quantum chemical approach to spin-orbit excitations and magnetic interactions in iridium oxides." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-160735.
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In the recent years, interest in TM oxides with 5d valence electrons has grown immensely due to the realization of novel spin-orbit coupled ground states. In these compounds, e.g., iridates and osmates, the intriguing situation arises where the spin-orbit and electron-electron interactions meet on the same energy scale. This has created a new window of interest in these compounds since the interplay of crystal field effects, local multiplet physics, spin-orbit couplings, and intersite hopping can offer novel types of correlated ground states and excitations. In 5d5 iridates, a spin-orbit entangled j = 1/2 Mott insulating state has been realized recently. A remarkable feature of such a ground state is that it gives rise to anisotropic magnetic interactions. The 2D honeycomb-lattice 213 iridium oxides, A2IrO3 (A=Li,Na), have been put forward to host highly anisotropic bond-dependent spin-spin interactions that resemble the Kitaev spin model, which supports various types of topological phases relevant in quantum computing. The 2D square-lattice 214 iridates Sr2IrO4 and Ba2IrO4 are, on the other hand, appealing because of their perceived structural and magnetic simi- larity to La2CuO4, the mother compound of the cuprate high-Tc superconductors. This has promoted the latter iridium oxide compounds as novel platforms for the search of high-Tc superconductivity.
To put such considerations on a firm footing, it is essential to quantify the different coupling strengths and energy scales, as they for instance appear in effective Hamiltonian descriptions of these correlated systems. Moreover, it is important to correctly describe their effects. In this thesis, the electronic structure and magnetic properties of 5d5 (mainly 214 and 213) iridates are studied using wave-function-based quantum chemistry methods. These methods are fully ab initio and are capable of accurately treating the electron-electron interactions without using any ad hoc parameters. The spin-orbit entangled j = 1/2 ground state in 214, 213 and other lower symmetry Sr3CuIrO6 and Na4Ir3O8 iridates is first analyzed in detail, by studying the local electronic structure of the 5d5 Ir4+ ion. We establish that the longer-range crystal anisotropy, i.e., low-symmetry fields related to ionic sites beyond the nearest neighbor oxygen cage, strongly influence the energies of Ir d levels. The ground state in all the compounds studied is j = 1/2 like with admixture from j ≃ 3/2 states ranging from 1 – 15 %. Further, the average j ≃ 1/2 → j ≃ 3/2 excitation energy we find is around 0.6 eV.
The NN magnetic exchange interactions we computed for 214 iridates are predominantly isotropic Heisenberg-like with J ~ 60 meV, 3 – 4 times smaller than found in isostructural copper oxides. However, the anisotropic interactions are an order of magnitude larger than those in cuprates. Our estimates are in excellent agreement with those extracted from experiments, e.g., resonant inelastic x-ray scattering measurements. For the 213 honeycomb-lattice Na2IrO3 our calculations show that the relevant spin Hamiltonian contains further anisotropic terms beyond the Kitaev-Heisenberg model. Nevertheless, we predict that the largest energy scale is the Kitaev interaction, 10 to 20 meV, while the Heisenberg superexchange and off-diagonal symmetric anisotropic couplings are significantly weaker. In the sister compound Li2IrO3, we find that the structural inequivalence between the two types of Ir-Ir links has a striking influence on the effective spin Hamiltonian, leading in particular to two very different NN superexchange pathways, one weakly AF (~ 1 meV) and another strongly FM (−19 meV). The latter gives rise to rigid spin-1 triplets on a triangular lattice.
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Rosser, David M. "Effects of Strain, Electron-Electron Interactions, and Spin-Orbit Coupling in Honeycomb Layered Materials." Thesis, California State University, Long Beach, 2017. http://pqdtopen.proquest.com/#viewpdf?dispub=10598952.
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Electronic transport and angle-resolved photoemission spectroscopy (ARPES) measurements were conducted on two different layered, honeycomb materials: graphene and sodium iridate (Na2IrO3). Graphene, the first two dimensional crystal observed in a laboratory, offers a system to explore novel quantum critical states theoretically predicted under the application of strain. Uniaxial strain was studied in suspended graphene using a microelectromechanical system (MEMS) via electronic transport. Strain was investigated as well by intercalation of C60 at the graphene-substrate (SiC) interface via ARPES. Sodium iridate is a relativistic Mott insulator proximate to the Kitaev model with unconventional electronic structure. An in-gap metallic feature was observed in ARPES measurements of Na2IrO3. Complementary evidence of a metallic conduction channel was observed in electronic transport measurements.
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Meetei, Oinam Nganba. "Metal-Insulator Transition and Novel Magnetism Driven by Coulomb Interactions, Spin-Orbit Coupling and Disorder." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405698402.
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Dang, Thi Huong. "Interfacial skew tunneling in group III-V and group IV semiconductors driven by exchange and spin-orbit interactions; Study in the frame of an extended k.p theory." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLX089/document.
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Nous avons étudié par des méthodes numériques et en théorie k.p avancée les propriétés tunnel d’électrons et de trous dans des systèmes modèles et hétérostructures composés de semi-conducteurs impliquant des interactions spin-orbite de volume. Nous démontrons que le couplage entre les interactions spin-orbite et d’échange à l’interface de jonctions tunnel résulte en un fort contraste de transmission de porteurs selon le signe de la composante de leur vecteur d’onde dans le plan de la jonction. Cet effet conduit à un effet tunnel anormal d’interface que nous appelons « Effet Hall Tunnel Anormal » (ATHE). De façon similaire, des processus tunnel non-conventionnels se manifestant sur des isolants topologiques ont été prédits par d’autres auteurs. Alors que l’ensemble de ces effets Hall anormaux sont liés aux interactions spin-orbite, les effets tunnel anormaux diffèrent des effets Hall tunnel, des effets Hall et des effets Hall de spin par la forte amplitude prédite ainsi que par des phénomènes de chiralité. Ces propriétés possèdent un lien nontrivial avec la symétrie du système. L’ensemble de ces résultats démontre l’existence d’une nouvelle classe d’effets tunnel qui devaient être étudiés expérimentalement dans un futur proche. En ce qui concerne la bande de valence, nous démontrons, en utilisant un Hamiltonien 14x14 prolongeant un modèle 2x2, que le calcul décrivant l’ATHE repose sur un traitement subtil des états dits « spurious » (états non-physiques) et nous donnons quelques éléments d’amélioration et de compréhension. Dans ce mémoire de thèse, nous développons deux méthodes numériques pour résoudre le problème des états spurious en développant en parallèle des méthodes k.p respectivement à 14 bandes et 30 bandes afin de décrire des matériaux semiconducteurs à gap indirect. Les calculs menés dans la bande de valence d’hétérostructures semiconductrice incluant interfaces et barrières tunnel (approches 6x6 et 14x14) sans centre de symétrie d’inversion mettent en évidence des propriétés d’asymétrie équivalente à celles obtenues dans la bande de conduction. De tels effets sont interprétés, dans le cadre de calculs de perturbation en transport basés sur des techniques de fonctions de Green, par des effets chiraux orbitaux lors du branchement tunnel des fonctions évanescentes dans la barrièreWe report on theoretical, analytical and computational investigations and k.p calculations of electron and hole tunneling, in model systems and heterostructures composed of exchange-split III-V semiconductors involving spin-orbit interaction (SOI). We show that the interplay of SOI and exchange interactions at interfaces and tunnel junctions results in a large difference of transmission for carriers, depending on the sign of their incident in-plane wave vector (k//): this leads to interfacial skew-tunneling effects that we refer to as Anomalous Tunnel Hall Effect (ATHE). In a 2x2 exchange-split band model, the transmission asymmetry (A) between incidence angles related to +k// and -k// wave vector components, is shown to be maximal at peculiar points of the Brillouin zone corresponding to a totally quenched transmission (A = 100%). More generally, we demonstrate the universal character of the transmission asymmetry A vs. in-plane wavevector component, for given reduced kinetic energy and exchange parameter, A being universally scaled by a unique function, independent of the spin-orbit strength and of the material parameters. Similarly, striking tunneling phenomena arising in topological insulators have just been predicted. While they all are related to the spin-orbit directional anisotropy, ATHE differs from the tunneling Hall effect, spontaneous anomalous, and spin Hall effects, or spin-galvanic effect, previously reported for electron transport, by its giant forward asymmetry and chiral nature. These features have non-trivial connection with the symmetry properties of the system. All these results show that a new class of tunneling phenomena can now be investigated and experimentally probed.When valence bands are involved, we show (using 14x14 Hamiltonian and within a 2x2 toy model) that ATHE accurate calculations rely on a subtle treatment of the spurious (unphysical) states and we give an insight into the topology of the complex band structure. We introduce two numerical methods to remove spurious states and successfully, include them in 30-band codes able to describe indirect bandgap group-IV semiconductors. Calculations performed in the valence bands of model heterostructures including tunnel barriers, in both 6x6 and 14x14 k.p Hamiltonians without inversion asymmetry, more astonishingly highlight the same trends in the transmission asymmetry which appears to be related to the difference of orbital chirality and to the related branching (overlap) of the corresponding evanescent wave functions responsible for the tunneling current. Besides, we built an analytical model and developed scattering perturbative techniques based on Green’s function method to analytically deal with electrons and holes and to compare these results with numerical calculations. The agreement between the different approaches is very good. In the case of holes, the asymmetry appears to be robust and persists even when a single electrode is magnetic
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Rozbicki, Emil Jerzy. "Effects of spin-orbit coupling and many-body interactions on the electronic structure of Sr₂RuO₄." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/3217.
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The aim of the project is to investigate the effects of spin-orbit coupling and many-body interactions on the band structure of the single-layered strontium ruthenate Sr₂RuO₄. This material belongs to the large family of strongly correlated electron systems in which electron-electron interaction plays a crucial role in determining the macroscopic properties. The experimental method used for this purpose is Angular Resolved Photoemission Spectroscopy (ARPES), which probes the single-particle spectral function and allows direct measurements of the quasi-particle band structure. The analysis is based on comparison of experimental data with electronic structure calculations. Typical methods for the band structure calculations including density functional theory (DFT) in the local density approximation (LDA) and tight-binding calculations (TB) are one-electron approximations and do not give insight into many-body interactions. However, comparing the measured band structures with calculated ones allows estimating the strength of the interactions in the considered system. In Chapter 1 the earlier work on Sr₂RuO₄, which is relevant to this project is presented. This chapter is an introduction to the data analysis and discussion of the results. In Chapter 2 we describe the experimental setup, theoretical principles of the measurement and summarize important improvements made during this project. In Chapter 3 we give a brief introduction into density functional theory and describe methods used within DFT to calculate the band structure. We further give a brief description of a tight binding model for Sr₂RuO₄. The bulk of this chapter is devoted to present the e ects of spin-orbit coupling on the band structure of Sr₂RuO₄. In particular, we use a tight binding model to simulate the anisotropy of the Zeeman splitting found experimentally. In Chapter 4 we present the ARPES results, their analysis and discussion. A particular focus is placed on the discussion of the surface layer Fermi surface topology and on the discovery of strong momentum dependance of the mass renormalization factors of the bulk β and γ bands.
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Paerschke, Ekaterina. "Interplay of Strong Correlation, Spin-Orbit Coupling and Electron-Phonon Interactions in Quasi-2D Iridium Oxides." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-235245.
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In the last decade, a large number of studies have been devoted to the peculiarities of correlated physics found in the quasi-two-dimensional square lattice iridium oxides. It was shown that this 5d family of transition metal oxides has strong structural and electronic similarities to the famous 3d family of copper oxides. Moreover, a delicate interplay of on-site spin-orbit coupling, Coulomb repulsion and crystalline electric field interactions is expected to drive various exotic quantum states. Many theoretical proposals were made in the last decade including the prediction of possible superconductivity in square-lattice iridates emerging as a sister system to high-Tc cuprates, which however met only limited experimental confirmation. One can, therefore, raise a general question: To what extent is the low-energy physics of the quasi-two-dimensional square-lattice iridium oxides different from other transition metal oxides including cuprates? In this thesis we investigate some of the effects which are usually neglected in studies on iridates, focusing on quasi-two-dimensional square-lattice iridates such as Sr2IrO4 or Ba2IrO4. In particular, we discuss the role of the electron-phonon coupling in the form of Jahn-Teller interaction, electron-hole asymmetry introduced by the strong correlations and some effects of coupling scheme chosen to calculate multiplet structure for materials with strong on-site spin-orbit coupling.
Thus, firstly, we study the role of phonons, which is almost always neglected in Sr2IrO4, and discuss the manifestation of Jahn-Teller effect in the recent data obtained on Sr2IrO4 with the help of resonant inelastic x-ray scattering. When strong spin-orbit coupling removes orbital degeneracy, it would at the same time appear to render the Jahn-Teller mechanism ineffective. We show that, while the Jahn-Teller effect does indeed not affect the antiferromagnetically ordered ground state, it leads to distinctive signatures in the spin-orbit exciton.
Second, we focus on charge excitations and determine the motion of a charge (hole or electron) added to the Mott insulating, antiferromagnetic ground-state of square-lattice iridates. We show that correlation effects, calculated within the self-consistent Born approximation, render the hole and electron case very different. An added electron forms a spin-polaron, which closely resembles the well-known cuprates, but the situation of a removed electron is far more complex. Many-body configurations form that can be either singlets and triplets, which strongly affects the hole motion. This not only has important ramifications for the interpretation of angle-resolved photoemission spectroscopy and inverse photoemission spectroscopy experiments of square lattice iridates, but also demonstrates that the correlation physics in electron- and hole-doped iridates is fundamentally different.
We then discuss the application of this model to the calculation of scanning tunneling spectroscopy data. We show that using scanning tunneling spectroscopy one can directly probe the quasiparticle excitations in Sr2IrO4: ladder spectrum on the positive bias side and multiplet structure of the polaron on the negative bias side. We discuss in detail the ladder spectrum and show its relevance for Sr2IrO4 which is in general described by more complicated extended t-J -like model. Theoretical calculation reveals that on the negative bias side the internal degree of freedom of the charge excitation introduces strong dispersive hopping channels encaving ladder-like features.
Finally, we discuss how the choice of the coupling scheme to calculate multiplet structure can affect the theoretical calculation of angle-resolved photoemission spectroscopy and scanning tunnelling spectroscopy spectral functions.
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Leary, Cody Collin 1981. "Measurement and control of transverse photonic degrees of freedom via parity sorting and spin-orbit interaction." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/10910.
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xv, 215 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.In this dissertation, several new methods for the measurement and control of transverse photonic degrees of freedom are developed. We demonstrate a mode sorter for two-dimensional (2-D) parity of transverse spatial states of light based on an out-of-plane Sagnac interferometer. The first experimental 2-D parity sorting measurements of Hermite-Gauss transverse spatial modes are presented. Due to the inherent phase stability of this type of interferometer, it provides a promising tool for the manipulation of higher order transverse spatial modes for the purposes of quantum information processing. We propose two such applications: the production of both spatial-mode entangled Bell states and heralded single photons, tailored to cover the entire Poincaré sphere of first-order transverse modes. In addition to the aforementioned transverse spatial manipulation based on free-space parity sorting, we introduce several more such techniques involving photons propagating in optical fibers. We show that when a photon propagates in a cylindrically symmetric waveguide, its spin angular momentum and its orbital angular momentum (OAM) interact. This spin-orbit interaction (SOI) leads to the prediction of several novel rotational effects: the spatial or time evolution of the photonic polarization vector is controlled by its OAM quantum number or, conversely, its spatial wave function is controlled by its spin. We demonstrate how these phenomena can be used to reversibly transfer entanglement between the spin and OAM degrees of freedom of two-particle states. In order to provide a deeper insight into the cause of the SOI for photons, we also investigate an analogous interaction for electrons in a cylindrical waveguide and find that each of the SOI effects mentioned above remain manifest for the electron case. We show that the SOI dynamics are quantitatively described by a single expression applying to both electrons and photons and explain their common origin in terms of a universal geometric phase associated with the interplay between either particle's spin and OAM. This implies that these SOI-based effects occur for any particle with spin and thereby exist independently of whether or not the particle has mass, charge, or magnetic moment.
Committee in charge: Daniel Steck, Chairperson, Physics; Michael Raymer, Member, Physics; Jens Noeckel, Member, Physics; Steven van Enk, Member, Physics; Andrew Marcus, Outside Member, Chemistry
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Andriati, Alex Valerio. "Condensados de Bose-Einstein com interação spin-órbita." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-21022018-185301/.
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Nesta dissertação são estudados Condensados de Bose-Einstein de átomos com pseudo-spin 1/2 cuja dinâmica orbital está acoplada a estes dois níveis de energia internos. A geração de tal sistema é possível induzindo transições entre os subníveis m_f = -1 e m_f = 0 do estado hiperfino atômico f = 1 usando um arranjo de lasers, os quais também introduzem junto uma dependência espacial dada por suas fases, as quais estão relacionadas a posição do átomo no campo, levando assim à interação acoplando spin e órbita. É considerado então um sistema unidimensional efetivo na mesma direção do acoplamento dos lasers, onde são estudado diferentes observáveis do estado fundamental, para uma varredura dos parâmetros presentes na equação, dando origem a três fases diferenciadas pela distribuição do momento. Foram determinadas estas fases do estado fundamental para interação atrativa, sendo elas modulada(striped), onda plana e de momento nulo, mostrando a localização onde cada uma ocorre no domínio de parâmetros da equação, através de diagramas de fase. São também mostrados, separadamente, observáveis relevantes como momento e desbalanço entre os estados internos nestas transições, os quais apresentaram variações bruscas, ditando valores críticos nos parâmetros, onde ocorrem. Posteriormente é estudado a dinâmica através de soluções do tipo sóliton, as quais não se propagam linearmente e são ditadas por oscilações do centro de massa e das populações, explorando diferentes situações iniciais.In the present dissertation it has been studied Bose-Einstein Condensation of atoms with 1/2 pseudo-spin whose the orbital dynamics is coupled to these two internal energy levels. The generation of such a system is done by inducing transitions between the sub-levels m_f = -1 and m_f = 0 from the hyperfine atomic state f = 1 using an arrangement of lasers, that also introduce a spacial dependence due to their phases, that changes accordingly the atom\'s position in the light field, conducting in this way to a interaction that couples orbital motion with spin. It is then considered an effective one dimensional system in the same direction of the laser coupling, where it has been studied different ground state observables, making a sweeping in the equation parameters, showing three typical phases based on momentum distribution. So far, it was determined these phases for attractive interactions, named striped, plane wave and zero momentum, determining as well the location where each one occurs in the equation\'s parameters through a phase diagram. It is also reported, separately, a few relevant observables as individual momentum of each population and the unbalance between the internal spin states, in the transition among these phases, whose the values present abrupt variations, dictating critical values for the parameters, where it occurs. Lately is presented a dynamical study with soliton like solutions, that do not linearly propagate and instead, shows a center of mass and unbalance oscillation, probing different initial conditions.
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Fiore, Mosca Dario. "Quantum magnetism in relativistic osmates from first principles." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019. http://amslaurea.unibo.it/17982/.
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The interplay between electron correlation, local distortions and Spin Orbit Coupling is one of the most attractive phenomena in condensed matter Physics and have stimulated much attention in the last decade. In Osmates double perovskites the coupling between electronic, structural and orbital degrees of freedom leads to the formation of an unconventional magnetic phase, whose precise origin and characteristics are still not understood. In particular strong Spin Orbit Coupling effect is believed to occur and have a crucial role in enhancing multipolar exchange interactions in a fashion similar to the more studied 4f electron systems. In this thesis, by means of first principles calculations, we study the structural, electronic and magnetic proprieties of the Mott insulating Ba2NaOsO6 with Osmium in 5d1 electron configuration within the fully relativistic Density Functional Theory plus on site Hubbard U (DFT + U) scheme. We find that the system is subjected to local symmetry breaking and that the magnetic ground state is strongly dependent on the on site Coulomb interaction. Furthermore, by mapping the energy onto a Pseudospin Hamiltonian, we are capable to prove that quadrupolar and octupolar exchanges play a significant role. We repeated the study for Ba2CaOsO6 with Os in 5d2 electronic configuration as a preliminary step for understanding if phase transitions are possible when Ba2NaOsO6 is doped.
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Nunner, Tamara S., N. A. Sinitsyn, Mario F. Borunda, V. K. Dugaev, A. A. Kovalev, Ar Abanov, Carsten Timm, et al. "Anomalous Hall effect in a two-dimensional electron gas." American Physical Society, 2007. http://hdl.handle.net/2237/11243.
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Zhang, Yao. "Experimental Measurements by Antilocalization of the Interactions between Two-Dimensional Electron Systems and Magnetic Surface Species." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/49020.
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Low-temperature weak-localization (WL) and antilocalization (AL) magnetotransport measurements are sensitive to electron interference, and thus can be used as a probe of quantum states. The spin-dependent interactions between controllable surface magnetism and itinerant electrons in a non-magnetic host provide insight for spin-based technologies, magnetic data storage and quantum information processing. This dissertation studies two different host systems, an In$_{0.53}$Ga$_{0.47}$As quantum well at a distance from the surface of a heterostructure, and an accumulation layer on an InAs surface. Both the systems are two-dimensional electron systems (2DESs), and possess prominent Rashba spin-orbit interaction caused by structural inversion asymmetry, which meets the prerequisites for AL. The surface local moments influence the surrounding electrons in two ways, increasing their spin-orbit scattering, and inducing magnetic spin-flip scattering, which carries information about magnetic interactions. The two effects modify the AL signals in opposing directions: the spin-flip scattering of electrons shrinks the signal, and requires a close proximity to the species, whereas the increase of spin-orbit scattering broadens and increases the signal. Accordingly, we only observe an increase in spin-orbit scattering in the study of the interactions between ferromagnetic Co$_{0.6}$Fe$_{0.4}$ nanopillars and the relatively distant InGaAs quantum well. With these CoFe nanopillars, a decrease in spin decoherence time is observed, attributed to the spatially varying magnetic field from the local moments. A good agreement between the data and a theoretical calculation suggests that the CoFe nanopillars also generate an appreciable average magnetic field normal to the surface, of value $\sim$ 35 G. We also performed a series of comparative AL measurements to experimentally investigate the interactions and spin-exchange between InAs surface accumulation electrons and local magnetic moments of rare earth ions Sm$^{3+}$, Gd$^{3+}$, Ho$^{3+}$, of transition metal ions Ni$^{2+}$, Co$^{2+}$, and Fe$^{3+}$, and of Ni$^{2+}$-, Co$^{2+}$-, and Fe$^{3+}$-phthalocyanines deposited on the surface. The deposited species generate magnetic scattering with magnitude dependent on their electron configurations and effective moments. Particularly for Fe$^{3+}$, the significant spin-flip scattering due to the outermost 3d shell and the fairly high magnetic moments modifies the AL signal into a WL signal. Experiments indicate a temperature-independent magnetic spin-flip scattering for most of the species except for Ho$^{3+}$ and Co$^{2+}$. Ho$^{3+}$ yields electron spin-flip rates proportional to the square root of temperature, resulting from transitions between closely spaced energy levels of spin-orbit multiplets. In the case of Co$^{2+}$, either a spin crossover or a spin-glass system forms, and hence spin-flip rates transit between two saturation regions as temperature varies. Concerning the spin-orbit scattering rate, we observe an increase for all the species, and the increase is correlated with the effective electric fields produced by the species. In both 2DESs, the inelastic time is inversely proportional to temperature, consistent with phase decoherence via the Nyquist mechanism. Our method provides a controlled way to probe the quantum spin interactions of 2DESs, either in a quantum well, or on the surface of InAs.Ph. D.
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Wang, Mengjia. "Spin-orbit interactions for steering Bloch surface waves with the optical magnetic field and for locally controlling light polarization by swirling surface plasmons." Thesis, Bourgogne Franche-Comté, 2019. http://www.theses.fr/2019UBFCD013/document.
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Ma thèse est consacrée aux nouveaux phénomènes nano-optiques et aux dispositifs basés sur l'interaction spin-orbite de la lumière (SOI). Tout d'abord, il a été démontré un SOI uniquement piloté par le champ magnétique de la lumière permettant de diriger avec précision les ondes de surface de Bloch, offrant ainsi une nouvelle manifestation du champ magnétique optique. Ensuite, nous avons proposé et démontré le concept de nano-antenne plasmonique hélicoïdale à ondes progressives (TW-HPA), c’est-à-dire un fil hélicoïdal en or étroit alimenté optiquement par une nano-antenne dipolaire dans une configuration « end-firing ». Une telle nano-antenne a été démontrée comme la première optique de polarisation sublongueur d’onde. L’agencement de TW-HPAs à l’échelle de quelques microns a permis de convertir « à la carte » un faisceau polarisé linéairement en une distribution de faisceaux directifs présentant des polarisations différentes définies de façon déterministe par la géométrie et les dimensions des nano-antennes. Par le biais d’un couplage en champ proche de quatre nano-antennes à hélicités opposées, nous avons obtenus une optique sublongueur d’onde permettant un degré de liberté dans le contrôle de la polarisation qui est interdit avec les composants et méthodes classiques basées sur l’exploitation de matériaux biréfringents ou dichroïques, ou de métamatériaux imitant ces propriétésMy thesis is devoted to novel nano-optical phenomena and devices based on spin-orbit interaction (SOI) of light. First, magnetic spin-locking, i.e., an SOI solely driven by the magnetic field of light, is demonstrated with Bloch surface waves. It provides a new manifestation of the magnetic light field. Then, we propose and demonstrate the concept of traveling-wave plasmonic helical antenna (TW-HPA), consisting of a narrow helical gold-coated wire non-radiatively fed with a dipolar nano-antenna. By swirling surface plasmons, the TW-HPA combines subwavelength illumination and polarization transformation. The TW-HPA is demonstrated to radiate on the subwavelength scale almost perfectly circularly polarized optical waves upon illumination with linearly polarized light. With this subwavelength plasmonic antenna, we developed strongly integrated arrays of point-light emissions of opposite handedness and tunable intensities. Finally, by coupling two couples of TW-HPAs of opposite handedness, we obtained new polarization properties so far unattainable
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Yokoyama, Takehito, Seiichiro Onari, and Yukio Tanaka. "Enhanced triplet superconductivity in noncentrosymmetric systems." American Physical Society, 2007. http://hdl.handle.net/2237/11291.
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García, Arellano Guadalupe. "Influence of the concentration and temperature on the spin relaxation time of donor-bound electrons immersed in a CdTe quantum well." Thesis, Sorbonne université, 2019. http://www.theses.fr/2019SORUS109.
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Ce travail présente une étude de l'influence de la concentration de dopage, de la température et du champ magnétique longitudinal sur le temps de relaxation de spin des électrons liés aux donneurs immergés au milieu d'un puits quantique (PQ) de CdTe. En insérant les donneurs dans un PQ, les règles de sélection optique de la lumière polarisée circulairement sont purifiées, ce qui permet un meilleur degré d'orientation optique des spins des électrons que dans les cristaux 3D. En utilisant une technique de rotation Faraday photo-induite, nous mesurons d’abord le temps de relaxation de spin des électrons liés aux donneurs pour différentes concentrations de dopage à basse température dans le régime isolant. Ensuite, pour évaluer les mécanismes de relaxation de spin dans notre système, nous calculons l'énergie d'échange d'une paire d'électrons liés aux donneurs immergés au milieu d'un PQ infini, pour toute distance inter-donneur et différentes épaisseurs. En utilisant ce calcul, nous expliquons le comportement expérimental comme une interaction de deux mécanismes : l’interaction hyperfine et l’anisotrope d’échange. De plus, nous déterminons la constante spin-orbite dans CdTe αso = 0.079. Ensuite, nous présentons le développement d’une expérience pompe-sonde étendue permettant de mesurer les temps de relaxation de spin à l’échelle microseconde. Nous discutons brièvement des premiers résultats expérimentaux pour le temps de relaxation de spin longitudinal d'électrons liés aux donneurs immergés dans un PQ de CdTe avec différentes concentrations de dopage. Enfin, nous étudions l'évolution en température de la relaxation de spin de 10 à 80 K. On explique le comportement expérimental en invoquant l'échange de spin entre les électrons localisés et le spin d'électrons promus en états de conduction. Le spin des électrons localisés subit l’effet des interactions hyperfine et anisotrope, le mécanisme de D’yakonov-Perel’ régit la relaxation de spin des électrons de conductionThis work presents a study of the influence of doping concentration, temperature and longitudinal magnetic field on the spin relaxation time of donor-bound electrons immersed in the middle of a CdTe quantum well (QW). By inserting the donors in a QW, the optical selection rules for circularly polarized light are purified, allowing a higher degree of optical orientation of the electron spins than in 3D crystals. By using a photo-induced Faraday rotation technique, we first measure the spin relaxation time of donor-bound electrons for different doping concentrations at low temperature in the insulating regime. Then, in order to evaluate the spin relaxation mechanisms in our system, we calculate the exchange energy of a pair of donor-bound electrons immersed in the middle of an infinite QW, for any inter-donor distance and for different thicknesses. By using this calculation, we explain the experimental behavior as an interplay of two mechanisms: hyperfine and anisotropic exchange interactions. Moreover we determine the CdTe spin-orbit constant: αso = 0.079. Afterwards we present the development of an extended pump-probe experiment allowing to measure spin relaxation times at the microsecond scale. We briefly discuss the first experimental results for the longitudinal spin relaxation time of donor-bound electrons immersed in a CdTe QW with different doping concentrations. Finally, we investigate the temperature evolution of the spin relaxation in the range 10-80 K. The experimental behavior is explained by invoking spin exchange between electron spins localized on donors and the spin of electrons promoted to conduction states. The spin of localized electrons undergoes the effect of hyperfine and anisotropic exchange interactions, the D’yakonov-Perel’ mechanism governs the spin relaxation of the conduction electrons
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Asmar, Mahmoud M. "Electronic and Spin Transport in Dirac-Like Systems." Ohio University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1437564830.
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Mutschler, Aurélie. "Le noyau-bulle de 34Si : Un outil expérimental pour étudier l’interaction spin-orbite ?" Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112157/document.
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L’interaction spin-orbite a permis de reproduire dans les modèles nucléaires théoriques, les nombres magiques N=28 et 50 observés dans les noyaux atomiques. Ces dernières décennies, l’étude expérimentale de noyaux exotiques a mis en évidence une évolution des nombres magiques loin de la vallée de stabilité. On peut alors se poser la question de l’évolution des potentiels d’interaction eux-mêmes, et en particulier de l’interaction spin-orbite. Si cette interaction a été historiquement incluse « à la main » dans les modèles de champ moyen « classiques », elle émerge cependant naturellement dans les modèles relativistes. La description de l’interaction spin-orbite est très similaire dans ces deux types de modèles, mais il subsiste a priori un désaccord du point de vue de sa dépendance en isospin : les modèles non-relativistes de type Hartree-Fock présentent en effet un potentiel spin-orbite dépendant fortement de l’isospin, contrairement aux modèles de type Relativistic Mean Field.En 2009, des calculs mettant en œuvre différents modèles théoriques ont prédit l’existence d’une « bulle », caractérisée par une déplétion en densité protonique centrale, dans le ³⁴Si. Ce dernier aurait une densité protonique très exotique, et bien différente de sa densité neutronique. Le ³⁴Si constituerait alors une sonde idéale de l’évolution du potentiel spin-orbite dans les systèmes présentant une forte asymétrie protons-neutrons. L’émergence d’un tel effet trouverait son origine dans la déplétion de l’orbitale protonique2s½, les orbitales s étant les seules à contribuer à la densité nucléaire centrale.Une expérience réalisée en Septembre 2012 à NSCL (MSU, Etats-Unis), a permis de mettre en évidence pour la première fois un effet de bulle nucléaire dans le ³⁴Si. L’étude des facteurs spectroscopiques des états peuplés lors des réactions d’arrachage de proton ou de neutron ³⁴Si(-1p) ³³Al et ³⁴Si(-1n) ³³Si indique que sa structure neutronique est très proche d’un système sans corrélations au-delà du champ moyen, tandis que son orbitale protonique est très faiblement occupée : n(2s½) = 0,16(4).Les réactions ³⁶S(-1p) ³⁵P et ³⁶S(-1n) ³⁵S ont été étudiées dans les mêmes conditions expérimentales. L’évolution de l’occupation n(2s½) mesurée entre le ³⁶S et le ³⁴Si, ainsi que la variation de l’écart en énergie des partenaires spin-orbite neutroniques 2p½-2p^3/2, mesurée entre ces deux noyaux dans une expérience antérieure, sont en faveur des modèles de champ moyen non-relativistes. La partie théorique de cette thèse a cependant montré que la différence de comportement de l’interaction spin-orbite entre modèles relativistes et non-relativistes est en fait un artefact causé par l’omission du terme d’échange dans les calculs de type Relativistic Mean Field. En effet, l’inclusion du terme de Fock dans les modèles relativistes permet de rétablir la dépendance en isospin du potentiel spin-orbite observée dans le cas non-relativisteThe spin-orbit interaction is essential for the reproduction of magic numbers N=28 and 50 in theoretical nuclear models. Over the past few decades, the experimental study of exotic nuclei has highlighted an evolution of magic numbers far from stability. One can then wonder about the evolution of nuclear potentials themselves, and in particular the one of spin-orbit interaction. Historically, this interaction was included « by hand » in mean field models, whereas it naturally arises in relativistic mean field models. The description of the spin-orbit interaction happens to be very similar in those two kinds of models, but there remains a disagreement regarding its isospin dependance. Indeed, Hartree-Fock models exhibit a spin-orbit potential which strongly depends on isospin, contrary to relativistic mean field models.In 2009, a proton bubble was predicted in ³⁴Si by means of several different nuclear models. This effect consists in a central proton central density depletion. ³⁴Si would exhibit a quite exotic proton density, and very different from its neutron density. This nucleus would then constitute an ideal probe to test the behaviour of the spin-orbit potential in systems with strong proton-neutron asymmetry. The appearance of such an effect would originate from the depletion of proton 2s½ orbitals, as s orbitals are the only ones contributing to the central density.An experiment which was performed in September 2012 at NSCL (MSU, United States) highlighted for the first time a proton bubble in ³⁴Si. The spectroscopic strengths of states populated in the knockout reactions ³⁴Si(-1p)³³Al and ³⁴Si(-1n)³³Si reveal that the neutron structure of ³⁴Si is close to the one of a system without beyond-mean-field correlations, whereas its proton orbital is only weakly occupied : n(2s½) = 0,16(4).The reactions ³⁶S(-1p)³⁵P and ³⁶S(-1n)³⁵S were studied in similar experimental conditions. The change in occupancy n(2s½) measured between ³⁶S and ³⁴Si, as well as the variation in the neutron spin-orbit splitting 2p½-2p^3/2 measured in an earlier experiment, suggest that non-relativistic models exhibit the right isospin dependance. The theoretical part of this thesis showed however that the difference in behaviour of the spin-orbit interaction between relativistic and non-relativistic model is actually an artefact caused by the omission of the exchange term in relativistic mean field calculations. Indeed, including the Fock term in relativistic models enables to restore the isospin dependance observed in the non-relativistic case
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Katukuri, Vamshi Mohan [Verfasser], den Brink Jeroen [Akademischer Betreuer] van, and Hermann [Akademischer Betreuer] Stoll. "Quantum chemical approach to spin-orbit excitations and magnetic interactions in iridium oxides / Vamshi Mohan Katukuri. Gutachter: Jeroen van den Brink ; Hermann Stoll. Betreuer: Jeroen van den Brink." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2015. http://d-nb.info/1069096342/34.
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Li, Mingguang. "High-resolution laser spectroscopy of the A²Pi - X²Sigma§+ system of CaOH and CaOD radicals, analysis of Renner-Teller, spin-orbit, K-type resonance and Fermi resonance interactions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1995. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ65807.pdf.
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Liu, Tianhan. "Strongly Correlated Topological Phases." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066403.
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Cette thèse porte principalement sur l'étude de modèles de fermions en interactions contenant un couplage spin-orbite. Ces modèles (i) peuvent décrire une classe de matériaux composés d'iridates sur le réseau en nid d'abeille ou (ii) pourraient être réalisés artificiellement dans des systèmes d’atomes froids. Nous avons étudié, dans un premier temps, le système à demi-remplissage avec l'interaction de Hubbard et un couplage spin-orbite anisotrope. Nous avons trouvé plusieurs phases: la phase isolant topologique pour de faibles corrélations, et deux phases avec des ordres magnétiques frustrés, l'ordre de Néel et l'ordre spiral, dans la limite de très fortes corrélations. La transition entre les régimes de faibles et de fortes corrélations est une transition de Mott dans laquelle les excitations électroniques se fractionnent en excitations de charge et de spin. Les charges sont localisées par l'interaction. Le secteur de spin présente de fortes fluctuations qui sont modélisées par un gaz d’instantons. Nous avons ensuite exploré la physique d'un système régi au demi-remplissage par le modèle de Kitaev-Heisenberg, qui présente une phase magnétique de type zig-zag. En dopant le système, autour du quart remplissage, la structure de bande présente de nouveaux centres de symétrie en plus de la symétrie d'inversion. Le couplage de spin de Kitaev-Heisenberg favorise alors la formation de paires de Cooper dans un état triplet autour de ces centres de symétrie. La condensation de ces paires de Cooper autour de ces vecteurs d'onde non triviaux se manifeste par une modulation spatiale du paramètre d'ordre supraconducteur, comme dans la supraconductivité de Fulde–Ferrell–Larkin–Ovchinnikov (FFLO). La dernière partie de la thèse propose et étudie une implémentation des phases topologiques dite de Haldane et de Kane-Mele dans un système avec deux espèces de fermions sur le réseau en nid d'abeille, stabilisée grâce à l’interaction RKKY médiée par l’espèce rapide et qui agit sur l’espèce lenteThis thesis is dedicated largely to the study of theoretical models describing interacting fermions with a spin-orbit coupling. These models (i) can describe a class of 2D iridate materials on the honeycomb lattice or (ii) could be realized artificially in ultra-cold gases in optical lattices. We have studied, in the first part, the half-filled honeycomb lattice model with on-site Hubbard interaction and anisotropic spin-orbit coupling. We find several different phases: the topological insulator phase at weak coupling, and two frustrated magnetic phases, the Néel order and spiral order, in the limit of strong correlations. The transition between the weak and strong correlation regimes is a Mott transition, through which electrons are fractionalized into spins and charges. Charges are localized by the interactions. The spin sector exhibits strong fluctuations which are modeled by an instanton gas. Then, we have explored a system described by the Kitaev-Heisenberg spin Hamiltonian at half-filling, which exhibits a zig-zag magnetic order. While doping the system around the quarter filling, the band structure presents novel symmetry centers apart from the inversion symmetry point. The Kitaev-Heisenberg coupling favors the formation of triplet Cooper pairs around these new symmetry centers. The condensation of these pairs around these non-trivial wave vectors is manifested by the spatial modulation of the superconducting order parameter, by analogy to the Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) superconductivity. The last part of the thesis is dedicated to an implementation of the Haldane and Kane-Mele topological phases in a system composed of two fermionic species on the honeycomb lattice. The driving mechanism is the RKKY interaction induced by the fast fermion species on the slower one
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Papandreou, Nicos. "Étude de la transition métal-isolant dans des films inhomogènes de Pd." Paris 11, 1989. http://www.theses.fr/1989PA112270.
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Nous avons étudié l'interférence entre le désordre à l'échelle macroscopique et microscopique sur les propriétés de transport électrique de films troués de Palladium. Les échantillons sont préparés par irradiation avec des ions lourds de moyenne énergie. Des mesures de résistance, de rétrodiffusion Rutherford et de microscopie électronique, réalisées in situ à différents stades de l'irradiation permettent d'obtenir les paramètres structuraux (libre parcours moyen électronique épaisseur et taux de couverture métallique) qui influencent la résistance. Un modèle décrivant la variation de la résistance avec la fluence d'irradiation est proposé. Les mesures électriques à basse température révèlent que les inhomogénéités macroscopiques amplifient les effets du désordre microscopique nous observons une transition métal-isolant avant le franchissement du seuil de percolation. A partir d'une analyse quantitative de la résistance en fonction de la température et du champ magnétique, nous discutons la modification des lois de transport dans le régime métallique et isolantWe have studied the effect of interference between microscopic and macroscopic disorder on the electronic transport properties of thin inhomogeneous palladium films, made up of both metallic clusters and holes. The samples were prepared by irradiation with heavy ions of medium energy. Irradiation creates damage, thins the film due to sputtering and, as a critical thickness is reached, creates holes. Measurements of resistance, Rutherford backscattering and electron microscopy, performed in situ at different steps of the irradiation allow us to deduce the structural parameters (electronic mean free path, thickness and metallic coverage) which govern the resistance. A model describing the evolution of the resistance with the lon fluence is proposed. Low-temperature electrical measurements reveal that macroscopic inhomogeneities amplify the effects of microscopic disorder. We observe a metal-insulator transition before the percolation threshold. A quantitative analysis of the temperature and magnetic field resistance dependences leads to a discussion of the change in transport mechanisms in both the metallic and insulating regimes
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Paerschke, Ekaterina [Verfasser], Jeroen van den [Akademischer Betreuer] Brink, Jeroen/van den [Gutachter] Brink, and Krzysztof [Gutachter] Wohlfeld. "Interplay of Strong Correlation, Spin-Orbit Coupling and Electron-Phonon Interactions in Quasi-2D Iridium Oxides / Ekaterina Paerschke ; Gutachter: Jeroen van den Brink, Krzysztof Wohlfeld ; Betreuer: Jeroen van den Brink." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://d-nb.info/1160875170/34.
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Pärschke, Ekaterina [Verfasser], Jeroen van den [Akademischer Betreuer] Brink, Jeroen/van den [Gutachter] Brink, and Krzysztof [Gutachter] Wohlfeld. "Interplay of Strong Correlation, Spin-Orbit Coupling and Electron-Phonon Interactions in Quasi-2D Iridium Oxides / Ekaterina Paerschke ; Gutachter: Jeroen van den Brink, Krzysztof Wohlfeld ; Betreuer: Jeroen van den Brink." Dresden : Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://d-nb.info/1160875170/34.
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Pletyukhov, Mikhail. "Semiclassical theory of spin-orbit interaction." [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969561032.
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Khoo, Jun Yong. "Introducing spin-orbit interaction in graphene." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/119929.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2018.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 131-146).
The excellent electron properties of graphene, an atomically-thin material with record-high carrier mobility and gate tunability, make it central to modern nanoscience. However, the spin-orbit interaction (SOI) naturally present in graphene is extremely weak and has yet to be observed experimentally. This presents an obstacle for accessing novel phenomena in transport and optics, in particular those related to topological properties. This thesis seeks to address this limitation by artificially introducing SOI in graphene sandwiched between other atomically-thin materials that can produce an interfacial SOI in graphene. In particular, it is demonstrated that a strong SOI, naturally present in the two-dimensional materials such as transition metal dichalcogenides (TMD), can be partially transferred to graphene via the proximity effect. We predict a range of novel phenomena arising in graphene bilayers with layer-asymmetric SOI induced by a proximal TMD layer. These include a gate-tunable SOI, a gate-tunable intrinsic valley-Hall conductivity, as well as a gate-tunable edge conductivity, to name just a few. These findings will facilitate exploring previously inaccessible spin-related phenomena in graphene and other van der Waals heterostructures.
by Jun Yong Khoo.
Ph. D.
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Amft, Martin. "Density Functional Theory Studies of Small Supported Gold Clusters and Related Questions : What a Difference an Atom Makes." Doctoral thesis, Uppsala universitet, Materialteori, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-133246.
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During the last decades the specific manipulation of matter on the (sub-) nanometer scale, also known as nanoscience, became possible by technologies such as the scanning tunneling microscope. Nanocatalysts, i.e. catalytic active structures of up to a few nanometers in size, belong to this rather new class of materials. Unlike ordinary ’macroscopic’ catalytic materials, the performance of nanocatalysts does not simply scale, for instance, with the surface to volume ratio of the active material. In this Thesis model nanocatalysts are investigated by means of ab-initio density functional theory calculations. In paper I, we explain the experimentally observed catalytic characteristics of small gold clusters, Au1-4, on a regular magnesium oxide terrace towards the oxidation of carbon monoxide by thoroughly studying the adsorption of CO and O2 on these clusters. In the subsequent paper II, we study the feasibility of a catalytic water-mediated CO oxidation reaction on Au1-4/MgO and find that this reaction mechanism is not assessable for Au2,4/MgO and unlikely for Au1,3/MgO. Papers III and IV concentrate on the reactivity of clusters in the gas phase. Particularly, we focus on the relative stability of Au13 isomers and its potential for O2 dissociation (paper III). We find the lowest energy isomers, which contain a triangular prism at their center surrounded by a ring of the remaining seven atoms, to be generally stable upon O2 adsorption. The dissociation of O2 at certain sites of Au13 is found to be exothermic. In paper IV we performed scans of the Born-Oppenheimer potential energy surfaces of neutral and charged Cu3, Ag3, and Au3 to explore the thermally excited vibrations of these trimers. While the Born-Oppenheimer surface of Cu3 exhibits one fairly deep energy minimum, it is comparatively flat with two shallow minima in the case of Ag3. Hence for Ag3 there exist many thermally accessible geometries in a wide range of angles and bond lengths. For Au3, two distinct energy minima appear, being well-separated by a barrier of 180 meV. Already at room temperature, we find bond lengths changes of up to 5% for the studied trimers. Choosing Au3 as a case study for the changed reactivity of thermally excited modes, we find CO to bind up to 150 meV stronger to the excited cluster. Gold deposited on graphene and graphite was observed to form larger aggregates. In paper V, we study the electronic structures, high mobility, and substrate-mediated clustering processes of Au1-4 on graphene. Already in the 1970s is was speculated that dispersion forces, i.e. van der Waals forces, significantly contribute to the adsorption energies of gold atoms on graphite. We accounted for van der Waals interactions in our density functional theory calculations (paper VI) and investigated the influence of these dispersion forces on the binding of copper, silver, and gold adatoms on graphene. While copper and gold show a mixed adsorption mechanism, i.e. chemical binding plus attraction due to the van der Waals forces, silver is purely physisorbed on graphene.Felaktigt tryckt som Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology 719
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Remmert, Sarah M. "Reduced dimensionality quantum dynamics of chemical reactions." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:7f96405f-105c-4ca3-9b8a-06f77d84606a.
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In this thesis a reduced dimensionality quantum scattering model is applied to the study of polyatomic reactions of type X + CH4 <--> XH + CH3. Two dimensional quantum scattering of the symmetric hydrogen exchange reaction CH3+CH4 <--> CH4+CH3 is performed on an 18-parameter double-Morse analytical function derived from ab initio calculations at the CCSD(T)/cc-pVTZ//MP2/cc-pVTZ level of theory. Spectator mode motion is approximately treated via inclusion of curvilinear or rectilinear projected zero-point energies in the potential surface. The close-coupled equations are solved using R-matrix propagation. The state-to-state probabilities and integral and differential cross sections show the reaction to be primarily vibrationally adiabatic and backwards scattered. Quantum properties such as heavy-light-heavy oscillating reactivity and resonance features significantly influence the reaction dynamics. Deuterium substitution at the primary site is the dominant kinetic isotope effect. Thermal rate constants are in excellent agreement with experiment. The method is also applied to the study of electronically nonadiabatic transitions in the CH3 + HCl <--> CH4 + Cl(2PJ) reaction. Electrovibrational basis sets are used to construct the close-coupled equations, which are solved via Rmatrix propagation using a system of three potential energy surfaces coupled by spin-orbit interaction. Ground and excited electronic surfaces are developed using a 29-parameter double-Morse function with ab initio data at the CCSD(T)/ccpV( Q+d)Z-dk//MP2/cc-pV(T+d)Z-dk level of theory, and with basis set extrapolated data, both corrected via curvilinear projected spectator zero-point energies. Coupling surfaces are developed by fitting MCSCF/cc-pV(T+d)Z-dk ab initio spin orbit constants to 8-parameter functions. Scattering calculations are performed for the ground adiabatic and coupled surface models, and reaction probabilities, thermal rate constants and integral and differential cross sections are presented. Thermal rate constants on the basis set extrapolated surface are in excellent agreement with experiment. Characterisation of electronically nonadiabatic nonreactive and reactive transitions indicate the close correlation between vibrational excitation and nonadiabatic transition. A model for comparing the nonadiabatic cross section branching ratio to experiment is discussed.
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Grap, Stephan Michael [Verfasser]. "The functional renormalization group for interacting quantum systems with spin-orbit interaction / Stephan Michael Grap." Aachen : Hochschulbibliothek der Rheinisch-Westfälischen Technischen Hochschule Aachen, 2013. http://d-nb.info/1038602432/34.
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Borunda, Bermudez Mario Francisco. "Topics in two-dimensional systems with spin-orbit interaction." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3225.
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Isic, Goran. "Electron transport in resonant tunnelling structures with spin-orbit interaction." Thesis, University of Leeds, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.545696.
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Pezo, Lopez Armando Arquimedes [UNESP]. "Electronic structure of two dimensional systems with spin-orbit interaction." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/151633.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
A realização experimental do grafeno em 2004 abriu as portas para os estudos de uma nova geração de materiais, estes chamados materiais bidimensionais são a expressão final do que poderíamos pensar em material plano (monocamada) que, eventualmente, podem ser empilhados para formar o bulk. O grafeno oferece uma grande variedade de propriedades físicas, em grande parte, como o resultado da dimensionalidade de sua estrutura, e pelas mesmas razões, materiais como Fosforeno (P), Siliceno (S), Nitreto de Boro hexagonal (hBN), dicalcogenos de metais de transição (TMDC), etc. São muito interessantes para fins teóricos, como para futuras aplicações tecnológicas que podem-se desenvolver a partir deles, como dispositivos de spintrônica e armazenamento. Neste trabalho o estudo desenvolvido são as propriedades eletrônicas dos materiais apresentados acima (grafeno, fosforeno e MoTe 2 ), e além disso, ja que o acoplamento spin-órbita aumenta à medida que o número atômico tambem aumenta, espera-se que este parâmetro desempenhe um papel na estrutura eletrônica, particularmente para os TMDC’s. Começamos descrevendo genéricamente esses três sistemas, isto é, para o grafeno, podemos usar uma abordagem tipo tight binding, a fim de encontrar a dispersão de energia para as quase-particulas perto do nível de Fermi (Equação de Dirac). Usando cálculos DFT estudou-se de forma geral as propriedades desses sistemas com a inclusão do espin órbita. Abordou-se cálculos para descrever os efeitos do acoplo spin órbita sobre os materiais isolados, tambem nas heterostruturas (duas camadas formadas por eles). Finalmente, tambem estudou-se a possibilidade de defeitos e sua possível influência sobre a estrutura eletrônica das heterostruturas.
The experimental realization of graphene in 2004 opened the gates to the studies of a new generation of materials, these so-called 2 dimensional materials are the final expression of what we could think of a plane material (monolayer) that eventually can be stacked to form a bulk. Graphene, the wonder material, offers a large variety of physical properties, in great part, as the result of the dimensionality of its structure, and for the same reasons, materials like phosphorene(P), silicene(S), hexagonal Boron Nitride (hBN), transition metal dichalcogenides(TMDC), etc. are very interesting for theoretical purposes, as for the future technological applications that we can develope from them, such as Spintronics and Storage devices. In this dissertation we theoretically study the electronic properties of the materials presented above (graphene, Phosphorene and MoTe2), and besides that, since the spin-orbit coupling strength increases as the atomic number does, we expect that this paremeter plays a role in the electronic structure, particularly for the TMDC. We start describing generically those three systems using density functional theory including the effect of spin orbit. We address calculations to describe the effects of spin orbit on the isolated materials as well as the heterostructures. Finally we also include the possibility of defects in graphene and their possible influence on the electronic structure of heterostructures.
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Pezo, Lopez Armando Arquimedes. "Electronic structure of two dimensional systems with spin-orbit interaction /." São Paulo, 2016. http://hdl.handle.net/11449/151633.
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Orientador: Alexandre Reily RochaBanca: Marcelo Takeshi Yamashita
Banca: Cedric Rocha Leão
Resumo: A realização experimental do grafeno em 2004 abriu as portas para os estudos de uma nova geração de materiais, estes chamados materiais bidimensionais são a expressão final do que poderíamos pensar em material plano (monocamada) que, eventualmente, podem ser empilhados para formar o bulk. O grafeno oferece uma grande variedade de propriedades físicas, em grande parte, como o resultado da dimensionalidade de sua estrutura, e pelas mesmas razões, materiais como Fosforeno (P), Siliceno (S), Nitreto de Boro hexagonal (hBN), dicalcogenos de metais de transição (TMDC), etc. São muito interessantes para fins teóricos, como para futuras aplicações tecnológicas que podem-se desenvolver a partir deles, como dispositivos de spintrônica e armazenamento. Neste trabalho o estudo desenvolvido são as propriedades eletrônicas dos materiais apresentados acima (grafeno, fosforeno e MoTe 2 ), e além disso, ja que o acoplamento spin-órbita aumenta à medida que o número atômico tambem aumenta, espera-se que este parâmetro desempenhe um papel na estrutura eletrônica, particularmente para os TMDC's. Começamos descrevendo genéricamente esses três sistemas, isto é, para o grafeno, podemos usar uma abordagem tipo tight binding, a fim de encontrar a dispersão de energia para as quase-particulas perto do nível de Fermi (Equação de Dirac). Usando cálculos DFT estudou-se de forma geral as propriedades desses sistemas com a inclusão do espin órbita. Abordou-se cálculos para descrever os efeitos do acoplo s... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The experimental realization of graphene in 2004 opened the gates to the studies of a new generation of materials, these so-called 2 dimensional materials are the nal expression of what we could think of a plane material (monolayer) that eventually can be stacked to form a bulk. Graphene, the wonder material, o ers a large variety of physical properties, in great part, as the result of the dimensionality of its structure, and for the same reasons, materials like phosphorene(P), silicene(S), hexagonal Boron Nitride (hBN), transition metal dichalcogenides(TMDC), etc. are very interesting for theoretical purposes, as for the future technological applications that we can develope from them, such as Spintronics and Storage devices. In this dissertation we theoretically study the electronic properties of the materials presented above (graphene, Phosphorene and MoTe2), and besides that, since the spin-orbit coupling strength increases as the atomic number does, we expect that this paremeter plays a role in the electronic structure, particularly for the TMDC. We start describing generically those three systems using density functional theory including the e ect of spin orbit. We address calculations to describe the e ects of spin orbit on the isolated materials as well as the heterostructures. Finally we also include the possibility of defects in graphene and their possible in uence on the electronic structure of heterostructures
Mestre
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Brozell, Scott Raymond. "Spin-orbit configuration interaction calculations of Actinide and Lanthanide Systems /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192447429836.
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Nilwala, Gamaralalage Premasiri Kasun Viraj Madusanka. "Electron Transport in Chalcogenide Nanostructures." Case Western Reserve University School of Graduate Studies / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=case1572259784431038.
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Magallanes, González Hernando. "Mechanical effects of light in presence of optical spin-orbit interaction." Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0437.
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Des interactions entre la matière et la lumière sont à l'origine de phénomènes opto-mécaniques. L'une des caractéristiques distinctives de l'interaction lumière-matière est l'interaction spin-orbite de la lumière. Cette dernière s'étudie au sein d'un domaine de recherche émergent consacré à l'étude des effets opto-mécaniques en présence de l'interaction entre la polarisation et des degrés de liberté spatiaux de la lumière. En particulier, ce travail vise à observer directement la manifestation (i) des forces latérales et (ii) des couples optiques gauches qui sont des effets opto-mécaniques contre-intuitifs. On utilise pour cela des milieux non homogènes et anisotropes comme ingrédients essentiels à la fabrication d’éléments optiques spin-orbite. Nous rapportons tout d'abord, les tentatives d’observations expérimentales directes, à partir des résultats préliminaires obtenus préalablement dans notre groupe de recherche. Nous présentons ensuite de nouvelles propositions d'expérimentations ainsi qu'une généralisation adaptée au cas des forces latérales. Par conséquent, nous rapportons d’une observation directe à l’échelle du millimètre des forces latérales optiques et des couples optiques gauches dépendantes du spin en effectuant une étude complète. Il ressort de l'analyse des deux phénomènes que leurs vitesses peuvent être augmentées en réduisant l'inertie ou la taille des éléments optiques spin-orbite au point de rendre les phénomènes significatifs à l'échelle microscopique et intéressants pour les applications technologiques. Nous faisons un rapport chronologique de notre travail expérimental consistant à observer le moment de force orienté à gauche à l'échelle du micromètre en utilisant des versions miniaturisées des échantillons précédents. Comme la dernière tentative n’était pas concluante, nous finissons par proposer de nouvelles stratégies prometteuses pour manipuler de tels micro-objetsInteractions between light and matter cause optomechanical phenomena, where a distinctive feature of light-matter interaction, namely, the spin-orbit interaction of light, takes place within an emerging research area dedicated to the study of optomechanical effects in the presence of the interplay between polarization and spatial degrees of freedom of light. In particular, this work aims to directly observe the manifestation of (i) lateral forces and (ii) left-handed torques, which are counterintuitive optomechanical effects, by using inhomogeneous and anisotropic media as a critical ingredient for the manufacture of spin-orbit optical elements. Hence, we report on their direct experimental observations attempts, starting from the preliminary results obtained in our group before this work, and then present our new proposals and further generalization to the case of lateral forces. Consequently, we report on a millimeter-scale direct observation of optical spin-dependent lateral forces and left-handed torques with a full study. From the analysis of both phenomena, it turns out that their speed can be increased by reducing the spin-orbit optical elements inertia or size, making the phenomena relevant at microscopic-scale and interesting for technological applications. Thus, we account for our experimental journey chronologically, to observe the left-handed torque at micrometer-scale with samples that correspond to miniaturized versions of previous ones. Since the last results were inconclusive, we finish by proposing new strategies of manipulation of such micro-elements with promising implementation
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Peters, John Archibald. "Ballistic Magnetotransport and Spin-Orbit Interaction InSb and InAs Quantum Wells." Ohio University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1143487911.
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Hakobyan, Davit. "Spin-orbit optomechanics of space-variant birefringent media." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0081/document.
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Ce travail consiste en l'étude de phénomènes optomécaniques en d'interaction spin-orbite de la lumière, en utilisant des milieux inhomogènes et anisotropes comme systèmes modèles, différents types de systèmes matériels étant considérés en pratique. En particulier,nous avons utilisé des défauts de cristaux liquides nématiques pour lesquels nous avons identifié expérimentalement d'un couple optique de nature spin-orbite conduisant à des modifications de champ d'orientation moléculaire du cristal liquide. Aussi, grâce à l'utilisation de verres nanostructurés artificiellement permettant un contrôle de l'interaction spin-orbite à la demande,nous mettons en évidence un phénomène de couple optique inverse qui est l'analogue angulaire des forces optiques dites négatives. Cet effet optomécanique contre-intuitif est démontré expérimentalement, d'une manière indirecte, grâce à la mise en place de diverses expériences de décalage en fréquence Doppler associées aux degrés de liberté de rotation. Enfin, nous présentons nos tentatives en vue de réaliser expérimentalement l'observation directe d'un couple optique inverse. Plusieurs options sont envisagées, qui comprennent à la fois des approches à base de matériaux métalliques ou diélectriques. De manière générale, cela implique la miniaturisation des systèmes considérés, ce qui est effectué à la fois à l'échelle millimétrique et micrométriqueThis work focuses on angular optomechanics driven by the spin-orbit interaction of light, using inhomogeneous and anisotropic media as model systems and different kinds of such material systems are considered in practice. In particular, we use nematic liquid crystal defects and report on the direct experimental observation of spin-orbit optical radiation torque that leads to distortion of molecular orientation pattern of the defects. Then, by using solid-state spin-orbit couplers of arbitrary order made of artificially nanostructured glasses, we unveil an optical torque reversal phenomenon that is the angular counterpart of so-called optical negative forces. This counterintuitive optomechanical effect is experimentally retrieved, in an indirect manner, via rotational Doppler frequency shift experiments. Finally, we report on our attempts to build up an experimental framework allowing the direct observation of optical torque reversal. Several options are considered, which include both metallic and dielectric approaches and involve sample miniaturization that has been explored at the millimeter and micrometer scale
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Ham, Woo Seung. "Spin-orbit Phenomena in Non-centrosymmetric Magnetic Multilayers." Kyoto University, 2019. http://hdl.handle.net/2433/242636.
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Karlsson, Henrik. "Interaction of sublevels in gated biased semiconductor nanowires." Thesis, Linköpings universitet, Teoretisk Fysik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-132380.
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Mesoscopic devices, such as nano-wires, are of interest for the next step in creating spintronic devices. With the ability to manipulate electrons and their spin, spintronic devices may be realised. To that end the different effects found in low-dimensional devices must be studied and understood. In this thesis the influence that lateral spin-orbit coupling (LSOC) has on a nanowire, with asymmetrical confinement potential, is studied. The nanowire is studied through a numerical approach, using the Hartree-Fock method with Dirac interactions to solve the eigenvalue problem of an idealised infinite nanowire. The nanowire has a split-gate that generates the electrostatic asymmetrical confinement potential. It is found that the lateral spin-orbit coupling has little to no effect without any longitudinal effects in the wire, such as source-drain bias. The electrons will spontaneously create spin-rows in the device due to spin polarization. The spin polarization is triggered by using LSOC, numerical noise or from a weak magnetic field.Mesoskopiska anordningar, som nano-trådar, tros vara ett viktigt steg för att skapa spinnelektronik. För att kunna skapa spinnelektronik behövs kunskap om hur elektroner kan manipuleras. Generellt måste därför existerande fenomen i nanoelektronik studeras. I denna avhandling studeras hur ''lateral spin-orbit koppling'' (LSOC) influerar en nanotråd som har en asymmetrisk potentialbarriär. Hartree-Fock metoden, med Dirac potential för elektron-elektron interaktioner, användes för att beräkna energinivåerna för en idealisk, oändligt lång nanotråd. Nanotråden har en split-gate som alstrar den elektrostatiska, asymmetriska potentialbarriären. "Lateral spin-orbit koppling" visar sig ha minimal effekt då longitudinella effekter, exempelvis spänning, saknas. Elektronerna placerar sig spontant i spinn-rader i tråden vid spontan spinn polarisation. Spinn polarisationen sätts igång av LSOC, numeriska störningar eller från svagt pålagt magnetfält.
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Wirthmann, André [Verfasser]. "Far-Infrared Photoconductivity Spectroscopy and Spin-Orbit Interaction in Semiconductor Heterostructures / André Wirthmann." Aachen : Shaker, 2007. http://d-nb.info/1166516830/34.
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Vitullo, Dashiell. "Propagation of Photons through Optical Fiber: Spin-Orbit Interaction and Nonlinear Phase Modulation." Thesis, University of Oregon, 2016. http://hdl.handle.net/1794/20708.
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We investigate two medium-facilitated interactions between properties of light upon propagation through optical fiber. The first is interaction between the spin and intrinsic orbital angular momentum in a linear optical medium. This interaction gives rise to fine structure in the longitudinal momenta of fiber modes and manifests in rotational beating effects. We probe those beating effects experimentally in cutback experiments, where small segments are cut from the output of a fiber to probe the evolution of both output polarization and spatial orientation, and find agreement between theoretical predictions and measured behavior.
The second is nonlinear optical interaction due to cross- and self-phase modulation between the complex-valued temporal amplitude profile of pump pulses and the amplitude profiles of generated signal and idler pulses in optical fiber photon-pair sources utilizing the four-wave mixing process named modulation instability. We develop a model including the effects of these nonlinear phase modulations (NPM) describing the time-domain wave function of the output biphoton in the low-gain regime. Assuming Gaussian temporal amplitude profiles for the pump pulse, we numerically simulate the structure of the biphoton wave function, in symmetric and asymmetric group velocity matching configurations. Comparing the overlap of the joint temporal amplitudes with and without NPM indicates how good of an approximation neglecting NPM is, and we investigate the effects of NPM on the Schmidt modes. We find that effects of NPM are small on temporally separable sources utilizing symmetric group velocity matching, but appreciably change the state of temporally entangled sources with the same group velocity matching scheme. For sources designed to produce entangled biphotons, our simulations suggest that NPM increases the Schmidt number, which may increase entanglement resource availability with utilization of a phase-sensitive detection scheme. We find that NPM effects on temporally separable sources designed with asymmetric group velocity matching produce non-negligible changes in the state structure. The purity is unaffected at perfect asymmetric group velocity matching, but if the pump is detuned from the correct wavelength, the purity degrades. The largest changes to the state due to NPM occur in long fibers with long pulse durations and low repetition rates.
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Gruenewald, John H. "TUNING THE EFFECTIVE ELECTRON CORRELATION IN IRIDATE SYSTEMS FEATURING STRONG SPIN-ORBIT INTERACTION." UKnowledge, 2017. https://uknowledge.uky.edu/physastron_etds/51.
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The 5d transition metal oxides have drawn substantial interest for predictions of being suitable candidates for hosting exotic electronic and magnetic states, including unconventional superconductors, magnetic skyrmions, topological insulators, and Weyl semimetals. In addition to the electron-electron correlation notable in high-temperature 3d transition metal superconductors, the 5d oxides contain a large spin-orbit interaction term in their ground state, which is largely responsible for the intricate phase diagram of these materials. Iridates, or compounds containing 5d iridium bonded with oxygen, are of particular interest for their spin-orbit split Jeff = 1/2 state, which is partially filled without the presence of any additional electron correlation. However, the comparable energetics between a small, finite electron correlation energy and the spin-orbit interaction make the band structure of iridates amenable to small perturbations of the crystalline lattice and ideal for exploring the interplay between these two interactions.
While altering the spin-orbit interaction strength of iridium is tenably not feasible, the electron correlation energy can be tuned using a variety of experimental techniques. In this dissertation, the electronic and magnetic properties of iridates at various electron correlation energies are studied by altering the epitaxial lattice strain, dimensionality, and the radius size of the A-site cation. These parameters tune the effective electronic bandwidth of the system, which is inversely proportional to the effective electron correlation energy. The lattice strain and the cationic radius size achieve this by altering the Ir-O-Ir bond angle between nearest neighbor Ir ions. In the case of dimensionality tuning, the effective bandwidth is controlled via the coordination number of each Ir ion.
In the first study, a metal-to-insulator transition is observed in thin films of the semi-metallic SrIrO3 as in-plane compressive lattice strain is increased. This observation is consistent with the expectation of compressive lattice strain increasing the effective correlation energy; however, optical spectroscopy spectra reveal the increase is not sufficient for opening an insulating Mott gap. In the second part, the effective correlation energy is adjusted using a dimensional confinement of the layered iridate Sr2IrO4. Here, the coordination number of each Ir ion is reduced using an a-axis oriented superlattice of one-dimensional IrO2 quantum stripes, where several emergent features are revealed in its insulating Jeff = 1/2 state. In the final study, the effective correlation is tuned in a series of mixed-phase pyrochlore iridate thin films, where the Ir atoms take a corner-shared tetrahedral configuration. Here, a transition between conducting to insulating magnetic domain walls is revealed as the correlation energy is increased via A-site chemical doping. Each of these studies sheds light on the pronounced role the effective correlation energy plays in determining the local subset of phases predicted for iridates and related systems featuring strong spin-orbit interactions.