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Tesis sobre el tema "Quantum magnetisms"

Autor: Grafiati

Publicado: 23 de noviembre de 2024

Última modificación: 31 de julio de 2025

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1

Catalano, Alberto Giuseppe. "Understanding and exploiting non-local effects in quantum spin chains." Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAF022.

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À l'aube de la seconde révolution quantique, comprendre et exploiter les phénomènes résultant de l'interaction entre la non-localité intrinsèque de la mécanique quantique et les interactions purement non-locales est d'une importance cruciale pour le développement de nouvelles technologies quantiques. Dans cette thèse, nous nous concentrerons principalement sur les effets non-locaux introduits par la frustration topologique (FT), une forme de frustration faible qui a été introduite pour la première fois dans le contexte des chaînes de spins quantiques antiferromagnétiques en appliquant les cond

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2

Joshi, Darshan Gajanan. "Magnetic quantum phase transitions: 1/d expansion, bond-operator theory, and coupled-dimer magnets." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-198634.

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In the study of strongly interacting condensed-matter systems controlled microscopic theories hold a key position. Spin-wave theory, large-N expansion, and $epsilon$-expansion are some of the few successful cornerstones. In this doctoral thesis work, we have developed a novel large-$d$ expansion method, $d$ being the spatial dimension, to study model Hamiltonians hosting a quantum phase transition between a paramagnet and a magnetically ordered phase. A highlight of this technique is that it can consistently describe the entire phase diagram of the above mentioned models, including the quantum

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3

Rezakhanlou, Karen. "Orbital magnetism and quantum chaos /." [S.l.] : [s.n.], 1995. http://library.epfl.ch/theses/?nr=1312.

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4

Brambleby, Jamie. "Quantum magnetism in coordination polymers." Thesis, University of Warwick, 2018. http://wrap.warwick.ac.uk/111284/.

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This thesis presents an experimental and theoretical examination of five polymeric quantum magnets. The first of these is Cu(pyrazine)(glycinate)ClO4, an exchange-coupled spin-dimer system that undergoes a powerful and continuous magnetocaloric effect (MCE) in a rapidly changing magnetic field H. The evolution of the sample temperature T with H must be accounted for in order to reconcile an apparent discrepancy between the results of magnetometry measurements performed in quasistatic and pulsed magnetic fields, and the MCE is likely to be an important consideration for pulsed-field experiments

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5

Aguilà, Avilés David. "Design, synthesis and study of coordination complexes for quantum computing." Doctoral thesis, Universitat de Barcelona, 2013. http://hdl.handle.net/10803/123544.

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This thesis presents different strategies for the design of molecular complexes with the requirements to be used as two-qubit quantum gates. The approaches followed towards the preparation of potential qubit systems have been carried out focusing on the synthesis of ligands with β-diketone coordination units, which are very versatile for the design of metallocluster assemblies. One of the main advantages of using this kind of ligands is that they can be easily prepared through simple Claisen condensation, providing different combinations and possibilities for the addition of big variety of don

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6

Steele, Andrew J. "Quantum magnetism probed with muon-spin relaxation." Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:030d7e91-f38e-433f-9539-652b0f4996cc.

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This thesis presents the results of muon-spin relaxation (µ<sup>+</sup><abbr>SR</abbr>) studies into magnetic materials, and demonstrates how these results can be exploited to quantify the materials’ low moments and reduced dimensionality. Dipole-field simulations, traditionally used to estimate likely muon sites within a crystal structure, are described. A novel Bayesian approach is introduced which allows bounds to be extracted on magnetic moment sizes and magnetic structures—previously very difficult using µ<sup>+</sup><abbr>SR</abbr>—based on reasonable assumptions about positions in which

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7

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 s

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8

Bühler, Adam [Verfasser]. "Quantum Simulator for Spin-Orbital Magnetism / Adam Bühler." München : Verlag Dr. Hut, 2016. http://d-nb.info/1097818373/34.

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9

Lorenz, Wolfram. "On the Spin-Dynamics of the Quasi-One-Dimensional, Frustrated Quantum Magnet Li2CuO2." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-71010.

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Die magnetischen Eigenschaften von Li2CuO2 sind seit mehr als zwei Jahrzehnten Gegenstand theoretischen und experimentellen Interesses. Über die genaue Natur der magnetischen Wechselwirkungen in diesem Isolator konnte jedoch keine Einigkeit erzielt werden. Während das Material von Seiten theoretischer Untersuchungen als quasi-eindimensionaler Magnet mit starken ferromagnetischen Kopplungen entlang der Kette verstanden wurde, legten experimentelle Studien dominierende dreidimensionale Zwischenkettenkopplungen nahe. Im Rahmen dieser Dissertation werden auf der Grundlage von Untersuchungen des ma

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10

Morris, Richard. "Studies towards quantum magnonics." Thesis, University of Oxford, 2017. http://ora.ox.ac.uk/objects/uuid:89784b64-de31-457f-b9b2-54125c862632.

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This thesis reports on recent results which pave the way for future experiments in the emerging field of quantum magnonics. Chapter 1 presents a brief outline of the field of magnonics, which provides the context in which quantum magnonics has begun to develop. Chapter 2 provides an introduction to the theory of spin waves, which is necessary to understand the experiments reported in the thesis. In Chapter 3, the experimental methods and materials used to carry out the investigations in the thesis are described. Chapter 4 describes the coupling of resonant magnon modes in a sphere of yttrium-i

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11

Jiang, Kun. "Strong Correlation, Topology in Unconventional Superconductors and Quantum Magnetism." Thesis, Boston College, 2018. http://hdl.handle.net/2345/bc-ir:107984.

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Thesis advisor: Ziqiang Wang<br>The discovery of high-Tc superconductivity in cuprates, quantum Hall effect greatly challenge the single-electron understanding of condensed matter physics. In contrast to phonon-mediated BCS mechanism, the unconventional high-Tc superconductivity is widely believed to come from strongly electronic correlation. Strong electron-electron repulsion leads to the interplay among spin, charge, orbital and lattice degrees of freedom, resulting in high-temperature superconductivity, charge or spin density wave, Mott insulator, orbital order, nematicity etc. On the other

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12

Manmana, Salvatore Rosario [Verfasser], and Thomas [Akademischer Betreuer] Pruschke. "Quantum Magnetism, Nonequilibrium Dynamics and Quantum Simulation of Correlated Quantum Systems / Salvatore Rosario Manmana ; Betreuer: Thomas Pruschke." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2017. http://d-nb.info/1132336805/34.

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13

Haines, Charles Robert Sebastian. "Pressure tuned magnetism in d- and f-electron materials." Thesis, University of Cambridge, 2012. https://www.repository.cam.ac.uk/handle/1810/282990.

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Quantum phase transitions (QPT) on the border of magnetism have provided a fertile hunting ground for the discovery of new states of matter, for example; the marginal Fermi Liquid and non Fermi Liquid states as well high T$_C$ cuprate and magnetically mediated superconductivity. In this thesis I present work on three materials in which it may be possible to tune the system through a magnetic QPT with the application of hydrostatic pressure. Although the details of the underlying physics are different in each of the materials, they are linked by the possibility of finding new states on the bord

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14

Henderson, John. "SPIN QUANTUM DYNAMICS IN MOLECULAR MAGNETS." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3535.

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Molecular magnets are ideal systems to probe the realm that borders quantum and classical physics, as well as to study decoherence phenomena in nanoscale systems. The control of the quantum behavior of these materials and their structural characteristics requires synthesis of new complexes with desirable properties which will allow probing of the fundamental aspects of nanoscale physics and quantum information processing. Of particular interest among the magnetic molecular materials are single-molecule magnets (SMMs) and antiferromagnetic (AFM) molecular wheels in which the spin state of the m

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15

Schossler, Matheus de Oliveira. "Dinâmica de operadores de dois spins no modelo XX." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/76/76131/tde-15092017-090718/.

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Propriedades dinâmicas de sistemas quânticos de muitos corpos é um tópico de grande interesse em física da matéria condensada. Estas propriedades nos dão informação sobre a propagação de excitações elementares e de mecanismos de relaxação em sistemas interagentes. Neste contexto, as funções de correlação tem se tornado ainda mais relevantes devido a experimentos em sistemas de átomos frios e íons armadilhados que medem diretamente no domínio temporal os comportamentos assintóticos no tempo. No entanto, até o momento a maioria dos estudos em cadeias de spin quânticas focaram-se em correlações d

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16

Hill, Richard John Allan. "Tunnelling into InAs quantum dots." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/10002/.

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This thesis describes an experimental study of the electronic properties of semiconductor heterostructure tunnel devices. InAs self-assembled quantum dots (QDs) are incorporated into the barrier layer of a GaAs/AlAs/GaAs tunnel diode. When a voltage, V, is applied across the device, we observe resonant features in the tunnel current, I, whenever an electron state in one of the qds comes into resonance with an occupied electron state in the emitter. We employ an electron state of a single qd as a spectroscopic probe of a two-dimensional electron system (2DES), from the Fermi energy to the subba

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17

Holmström, Erik. "Magnetism and Structure in Metallic Multilayers." Doctoral thesis, Uppsala University, Department of Physics, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3556.

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<p>The interplay between magnetism and structure has been studied in magnetic multilayers by electronic structure calculations based on density functional theory and analyzed in terms of models. The main ideas behind the Korringa-Kohn-Rostocker Green’s function method are described and the implementation of the coherent potential approximation is outlined.</p><p>A simple model for the bilinear magnetic interlayer coupling in metallic multilayers is derived that elucidates the main characteristics of the effect such as coupling period and origin of damping. An analysis of two exotic effects on

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18

Radovanovic, Pavle V. "Synthesis, spectroscopy, and magnetism of diluted magnetic semiconductor nanocrystals /." Thesis, Connect to this title online; UW restricted, 2004. http://hdl.handle.net/1773/8494.

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19

Moroni, Dennis. "Unconventional magnetism and quantum criticality in the hexagonal Laves phase NbFeâ‚‚." Thesis, Royal Holloway, University of London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.430434.

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20

Rahn, Marein. "Magnetism in quantum materials probed by X-ray and neutron scattering." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:a20ff25c-bc04-44a2-8a29-d5236a06bd83.

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In his programmatic article More Is Different (1972), Nobel laureate P. W. Anderson captured the fundamental interest in quantum matter in a nutshell. The central motive in this field is emergence. In the inaugural volume of the homonymous journal, J. Goldstein defined this as "the arising of novel and coherent structures, patterns and properties during the process of self-organization in complex systems". Famously, the idea that the "the whole is greater than the sum of its parts" goes back to Aristotle's metaphysics, and it has served as a stimulating concept in 19th century biology, economi

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21

Shevchenko, Pavel Physics Faculty of Science UNSW. "Quantum Phenomena in Strongly Correlated Electrons Systems." Awarded by:University of New South Wales. Physics, 1999. http://handle.unsw.edu.au/1959.4/32669.

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Quantum phenomena in high-Tc superconductors and dimerized quantum Heisenberg antiferromagnets are studied analytically in this thesis. The implications of the Fermi surface consisting of the disjoint pieces, observed in cuprate superconductors, are considered. It is demonstrated that in this case the g-wave superconducting pairing is closely related to d-wave pairing. The superconductivity in this system can be described in terms of two almost degenerate superconducting condensates. As a result a new spatial scale lg, much larger than the superconducting correlation length x, arises and a

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22

Rodríguez, Karen [Verfasser]. "Non-equilibrium dynamics and quantum magnetism in 1D optical lattices / Karen Rodríguez." Hannover : Technische Informationsbibliothek und Universitätsbibliothek Hannover, 2011. http://d-nb.info/1011397145/34.

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23

Bühler, Adam [Verfasser], and Hans Peter [Akademischer Betreuer] Büchler. "Quantum simulator for spin-orbital magnetism / Adam Bühler ; Betreuer: Hans Peter Büchler." Stuttgart : Universitätsbibliothek der Universität Stuttgart, 2016. http://d-nb.info/1118368312/34.

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24

Murmann, Simon [Verfasser], and Selim [Akademischer Betreuer] Jochim. "Few-particle quantum magnetism with ultracold atoms / Simon Murmann ; Betreuer: Selim Jochim." Heidelberg : Universitätsbibliothek Heidelberg, 2015. http://d-nb.info/118060864X/34.

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25

Jo, Gyu-Boong. "Quantum coherence and magnetism in bosonic and fermionic gases of ultracold atoms." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/63010.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2010.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 168-185).<br>In this thesis, two sets of experimental studies in bosonic and fermionic gases are described. In the first part of the thesis, itinerant ferromagnetism was studied in a strongly interacting Fermi gas of ultracold atoms. The observation of nonmonotonic behavior of lifetime, kinetic energy, and size for increasing repulsive interactions provides strong evidence for a phase transition to a ferromagnetic state. Our observa

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26

Chisnell, Robin Michael Daub. "Neutron scattering and thermodynamic studies of quantum magnetism on the kagomé lattice." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/95868.

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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, 2014.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 191-198).<br>The geometry of the kagome lattice leads to exciting novel magnetic behavior in both ferromagnetic and antiferromagnetic systems. The collective spin dynamics were investigated in a variety of magnetic materials featuring spin-1/2 and spin-1 moments on kagome lattices using neutron scattering and thermodynamic probes. Both ferromagnetic and antiferromagnetic systems were studied. Cu(1,3-bdc) is an organometallic

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27

Gouveia, José Daniel Lago da Silva Neves. "Magnetic properties of quantum electronic systems with non-trivial geometries." Doctoral thesis, Universidade de Aveiro, 2017. http://hdl.handle.net/10773/21058.

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Doutoramento em Física<br>O modelo de Hubbard é um dos modelos mais simples para descrever o movimento e a interacção de electrões em sólidos. Tem sido largamente estudado pelas suas aplicações na descrição de condutores orgânicos e na procura de supercondutividade a cada vez mais altas temperaturas. O objectivo desta tese é contribuir para a melhor compreensão do comportamento do modelo de Hubbard a duas dimensões quando a geometria da rede é alterada, nomeadamente torcendo as condições de fronteira ou introduzindo frustração geométrica. Começa-se por fazer uma extensão do diagrama de

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28

Coak, Matthew. "Quantum tuning and emergent phases in charge and spin ordered materials." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/280284.

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A major area of interest in condensed matter physics over the past decades has been the emergence of new states of matter from strongly correlated electron systems. A few limited examples would be the emergence of unconventional superconductivity in the high-T$_c$ superconductors and heavy-fermion systems, the appearance of the skyrmion magnetic vortex state in MnSi and magnetically mediated superconductivity in UGe$_2$. While detailed studies of many of the emergent phases have been made, there are still many gaps in understanding of the underlying states and mechanisms that allow them to for

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29

Marshall, Robin Alexander. "Critical behaviour and quantum properties in (Ga,Mn)As." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13114/.

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pintronics is a rapidly developing field in solid state physics based on the quantum property of spin angular momentum. It has the potential to offer a new generation of electronic devices exploiting spin properties instead of, or in addition to, charge. Such quantum-based devices are expected to demonstrate significant advantages over traditional charge based electronics with a promise of faster data processing speeds and lower power consumption. One of the most widely studied spintronic materials is the dilute magnetic semiconductor gallium manganese arsenide ((Ga,Mn)As). This continues to b

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30

Brown, Adam L. "Transport and optical effects in self-assembled quantum dot devices." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10898/.

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This thesis describes a theoretical and numerical study of quantum transport and optical effects through an array of self-assembled InAs quantum dots grown in the intrinsic region of a GaAs p-i-n junction. We present a numerical simulation of this system and compare the generated transport and elecroluminescence results to recent experimental data. The simulation first calculates the quantum tunnelling, excitonic recombination, and relaxation rates within the dots, and then uses a stochastic model to simulate carriers entering and leaving the array. We highlight a number of features within the

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31

Vela, Llausí Sergi. "Computational Modeling of Molecular Magnetic Materials." Doctoral thesis, Universitat de Barcelona, 2014. http://hdl.handle.net/10803/285357.

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Molecular materials have raised much interest in the last decades in the quest for new multifunctional devices. Among the multiple properties that those materials may present, one of the most typical is magnetism, which arises from the presence of unpaired electrons in the molecules that constitute the three-dimensional crystal. Magnetism has a macroscopic observable, the magnetic susceptibility (Ji), which is usually rationalized in terms of a set of JAB magnetic interactions between pairs of molecules. However, any experimental technique allows for such direct correspondence and, thus, the e

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32

Chaggar, Amrik Richard. "Tunneling injection and recombination of carriers in self-assembled quantum dots." Thesis, University of Nottingham, 2009. http://eprints.nottingham.ac.uk/10757/.

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This thesis describes an experimental investigation of the resonant injection of carriers into self-assembled indium arsenide (InAs) quantum dots incorporated in the intrinsic region of gallium arsenide (GaAs) p-i-n resonant tunneling diodes, and of the resulting electroluminescence spectrum associated with carrier recombination in the quantum dots, wetting layer and GaAs matrix. A series of devices of different designs have been measured and it is shown that bipolar resonant injection, i.e. resonant injection of both electrons andholes, into the zero-dimensional states provided by the InAs qu

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33

Albring, Morten. "Towards quantum information processing with Cr3+ based heterometallic clusters." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/towards-quantum-information-processing-with-cr3-based-heterometallic-clusters(6ff7e303-ca75-4632-986d-48bea42d96e3).html.

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An investigation of the electronic structure of some transition metal clusters comprising anti-ferromagnetically coupled, heterometallic arrays of eight metal ions that are wheel-shaped, is reported. The compounds were synthesized and provided by Dr. Grigore Timco of The University of Manchester and are formulated by their metal content as Cr7M, where M = a divalent 3d metal. Two families of wheels are the subject of this research, defined ‘green’ and ‘purple’ from their physical appearance. Within each family, the compounds are all isostructural. From simulation using a single Hamiltonian for

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34

Bharadwaj, Sripoorna Paniyadi Krishna. "Theoretical Study of Spin-wave Effects in Quantum Ferromagnets." Thesis, University of Oregon, 2017. http://hdl.handle.net/1794/22640.

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In this dissertation, we examine quantum ferromagnets and determine various effects of the magnetic Goldstone modes or "magnons'' in these systems. Firstly, we calculate the magnon contribution to the transport relaxation rate of conduction electrons in metallic ferromagnets and find that at asymptotically low temperatures, the contribution behaves as T^2 exp(-T_0/T) and not as T^2 predicted previously. To perform these calculations, we derive and use a very general effective theory for metallic ferromagnets. This activation barrier-like behavior is due to the fact that spin waves only coupl

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35

Hooley, Chris. "The Kagome antiferromagnet and related models : studies in low-dimensional geometrically frustrated quantum magnetism." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301860.

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36

Baez, Maria Laura [Verfasser]. "Numerical methods for frustrated magnetism : from quantum to classical spin systems / Maria Laura Baez." Berlin : Freie Universität Berlin, 2018. http://d-nb.info/1170876846/34.

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37

Babkevich, Peter. "Quantum materials explored by neutron scattering." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:5f6ef05d-e846-47e1-b59f-864ea4fa2f3f.

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This thesis describes neutron scattering experiments on strongly correlated systems exhibiting a range of emergent phenomena: antiferromagnetism, charge order, superconductivity and multiferroicity. I have examined the La_{2}CoO_{4} compound which is a Mott insulator and orders antiferromagnetically near room temperature. The La_{2}CoO_{4} sample was studied using spherical neutron polarimetry and I present magnetic structure models to describe the two antiferromagnetic phases of the compound. Furthermore, the magnetic fluctuations have been investigated using neutron time-of-flight technique.

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38

Hennequin, Barbara. "Aqueous near infrared fluorescent composites based on apoferritin-encapsulated PbS quantum dots." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/11071/.

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Quantum dots offer a number of advantages over standard fluorescent dyes for monitoring biological systems including high luminescence, stability against photobleaching, and a wide range of fluorescence wavelengths from blue to infrared depending on the particle size. In this work, we investigated in using the protein cage apoferritin as a template for the synthesis of colloidal quantum dots. We obtained apoferritin after reductive dissolution of the ferritin iron core and showed that the protein structure was left intact during this process. We further studied the solubility of ferritin, apof

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39

Johnsen, Sebastian. "Low-dimensional Magnetism in Novel 2D Honeycomb Materials." Thesis, KTH, Tillämpad fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300902.

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A Kitaev quantum spin liquid is a phase of matter predicted to host excitations that can be used to preform fault-tolerant quantum computation. Though the theoretical prediction of such a state is on firm footing, its realisation in real materials has proven to be elusive. Recent developments have suggested honeycomb materials consisting of 3d transition metal ions as possible candidates. The focus of this thesis is the magnetic properties of one such material, K2Ni2–xCoxTeO6. It is part of a family of layered two dimensional materials consisting of honeycomb structured transition metal layers

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40

Mishra, Shantanu, Doreen Beyer, Reinhard Berger, et al. "Topological defect-induced magnetism in a nanographene." American Chemical Society, 2019. https://tud.qucosa.de/id/qucosa%3A73172.

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The on-surface reactions of 10-bromo-10'-(2,6-dimethylphenyl)-9,9'-bianthracene on Au(111) surface have been investigated by a combination of bond-resolved scanning tunneling microscopy, scanning tunneling spectroscopy, and tightbinding and mean-field Hubbard calculations. The reactions afford the synthesis of two open-shell nanographenes (1a and 1b) exhibiting different scenarios of all-carbon magnetism. 1a, an allbenzenoid nanographene with previously unreported triangulenelike termini, contains a high proportion of zigzag edges, which endows it with an exceedingly low frontier gap of 110 me

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41

Corre, Vincent. "Magnetism in spin-1 Bose-Einstein condensates with antiferromagnetic interactions." Thesis, Paris, Ecole normale supérieure, 2014. http://www.theses.fr/2014ENSU0020/document.

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Dans cette thèse nous étudions expérimentalement les propriétés magnétiques de condensats de sodium de spin 1 à l'équilibre. Dans ce système les atomes peuvent occuper chacun des trois états Zeeman caractérisés par la projection de leur spin sur l'axe de quantification m=+1,0,-1. Nous mesurons l'état de spin à N particules du système en fonction du champ magnétique appliqué et et de la magnétisation (différence entre les populations des états m=+1 et m=-1) du nuage atomique. Nos mesures sont en très bon accord avec la prédiction de la théorie de champ moyen, et nous identifions deux phases mag

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42

Sandoildo, Freitas Tenório Antônio. "Phase transitions and thermodynamics of quasione- dimensional quantum rotor and spin systems." Universidade Federal de Pernambuco, 2009. https://repositorio.ufpe.br/handle/123456789/6664.

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Made available in DSpace on 2014-06-12T18:06:41Z (GMT). No. of bitstreams: 2 arquivo945_1.pdf: 1972275 bytes, checksum: faf69ec63b01c315fa88949dbaf22651 (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2009<br>Sandoildo Freitas Tenório, Antônio; Domingues Coutinho Filho, Maurício. Phase transitions and thermodynamics of quasione- dimensional quantum rotor and spin systems. 2009. Tese (Doutorado). Programa de Pós-Graduação em Física, Universidade Federal de Pernambuco, Recife, 2009.

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Napolitano, Mario. "Interaction-based nonlinear quantum metrology with a cold atomic ensemble." Doctoral thesis, Universitat Politècnica de Catalunya, 2014. http://hdl.handle.net/10803/144558.

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In this manuscript we present an experimental and theoretical investigation of quantum-noise-limited measurement by nonlinear interferometry, or from another perspective, quantum-noise-limited interaction-based measurement. The experimental work is performed using a polarization-based quantum interface between propagating light pulses and cold rubidium-87 atoms trapped in an optical dipole trap. We first review the theory of quantum metrology and estimation theory, and we describe theoretical proposals for nonlinear quantum metrology as developed by the group of Carlton M. Caves in the Uni

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Adhikari, Ram Bahadur. "Superconductivity and Magnetism in Selected Filled Skutterudites and Heavy Fermion Systems." Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent16173874994732.

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Garlatti, E. "QUANTUM EFFECTS IN MOLECULAR NANOMAGNETS: FROM THEORY TO APPLICATIONS." Doctoral thesis, Università degli Studi di Milano, 2014. http://hdl.handle.net/2434/231098.

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Molecular nanomagnets have attracted the attention of the scientific community since they represent model systems to study many quantum phenomena, such as quantum entanglement and decoherence. They are also interesting for their envisaged technological applications, including magnetic refrigeration, high-density information storage and quantum information processing. Driven by these motivations, the present Thesis focuses on the study of magnetic properties and spin dynamics of different classes of molecular nanomagnets, with the purpose to understand their quantum behavior and their potential

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Dickinson, Laurie Alan. "Studies of magneto-tunneling into donor states and of the breakdown of the quantum Hall effect." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/14393/.

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This thesis describes an experimental investigation and analysis of two topical problems in condensed matter physics: 1.) the effect of a magnetic field on quantum states of an electron bound to a shallow donor impurity in a quantum well heterostructure and 2.) the breakdown of the quasi-dissipationless state of the integer quantum Hall effect. Two introductory chapters describe important material parameters and the experimental equipment and techniques used. Magneto-tunneling spectroscopy (MTS) is used to probe the spatial form of the eigenfunction of electrons bound in the ground state of a

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Notbohm, Susanne. "Spin dynamics of quantum spin-ladders and chains." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/403.

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Wheeler, Elisa Maria da Silva. "Neutron scattering from low-dimensional quantum magnets." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:a8411774-4a3e-4fc3-80a1-d7e8612cba71.

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Neutron scattering measurements were used to investigate the magnetic and crystal structure and magnetic excitations of three compounds characterized as low-dimensional quantum magnets. The materials are frustrated systems with low spin quantum number. The first was a powder sample of AgNiO<sub>2</sub>. The Ni ions form a triangular lattice antiferromagnet in which, according to the published crystal structure, both the orbital order and magnetic couplings are frustrated. However, it is shown here that there was a small distortion of the crystal structure at 365 K, which is proposed to result

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Vougalter, Vitali. "Diamagnetic behavior of sums of Dirichlet eigenvalues." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/28034.

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Woolfson, Robert. "Spins in rings : new chemistry and physics with molecular wheels." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/spins-in-rings-new-chemistry-and-physics-with-molecular-wheels(1cce143a-105e-4f8c-ac19-388f793fddc4).html.

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This thesis explores the synthesis and characterisation of a range of molecular wheels containing unpaired electron spins. These molecular spin systems are of considerable interest, both for the insight they provide into the physics of such systems and for their potential as quantum bits ("qubits") in a quantum information processing device. In particular, this thesis explores using these wheels to meet criteria 1 and 5 of the DiVincenzo criteria. The synthesis of a novel homometallic and nonametallic ring of CrIII ions is introduced, along with extensive physical characterisation. Inelastic N

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