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Academic literature on the topic 'Kagome lattices'

Author: Grafiati

Published: 4 June 2021

Last updated: 14 February 2022

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Journal articles on the topic "Kagome lattices"

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Mai, S. P., and N. A. Fleck. "Reticulated tubes: effective elastic properties and actuation response." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, no. 2103 (November 18, 2008): 685–708. http://dx.doi.org/10.1098/rspa.2008.0328.

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The structural performance is explored for a reticulated circular tube made from a periodic lattice: triangulated; hexagonal; Kagome; and square lattices. The finite-element (FE) method is used to determine the macroscopic bending, torsional and axial rigidities of each tube. Additional insight is obtained by examining the structural mechanics of the pin-jointed version of each topology. For all pin-jointed lattices considered, no states of self-stress exist. However, collapse mechanisms do exist for all reticulated tubes, and for the Kagome and hexagonal lattices some of these mechanisms produce macroscopic generalized strain. These strain-producing collapse modes are additional to those observed in the planar version of these lattices. Consequently, the structural rigidities of tubes with walls made from the rigid-jointed Kagome lattice or hexagonal lattice are less than those predicted from the in-plane effective properties of these two lattices. The morphing capacity of reticulated tubes is also explored by replacing a single bar with an actuator in the FE simulations. The actuation stiffness of the structure is defined by the stiffness of the reticulated tube in resisting extension by the actuated bar. The actuation stiffness is explored as a function of the type of lattice, number of unit cells around the circumference, orientation of the actuated bar and of the bar stockiness. In all cases, the macroscopic shape change of the tube can be idealized as a combination of a local rotation, axial extension, axial twist and shear displacement of the cross-section.

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Wu, F. Y., and Fa Wang. "Dimers on the kagome lattice I: Finite lattices." Physica A: Statistical Mechanics and its Applications 387, no. 16-17 (July 2008): 4148–56. http://dx.doi.org/10.1016/j.physa.2008.02.054.

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LEE, S. F., and K. Y. LIN. "SPONTANEOUS MAGNETIZATION OF THE ISING MODEL ON THE GENERAL UTIYAMA LATTICE." Modern Physics Letters B 07, no. 29n30 (December 30, 1993): 1903–10. http://dx.doi.org/10.1142/s0217984993001910.

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The spontaneous magnetization of the two-dimensional Ising model on the general Utiyama lattice is derived exactly. Our results include the checkerboard, kagome, 4–8, and 3–12 lattices as special cases.

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Sanders, M. B., J. W. Krizan, and R. J. Cava. "RE3Sb3Zn2O14 (RE = La, Pr, Nd, Sm, Eu, Gd): a new family of pyrochlore derivatives with rare earth ions on a 2D Kagome lattice." Journal of Materials Chemistry C 4, no. 3 (2016): 541–50. http://dx.doi.org/10.1039/c5tc03798k.

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RE₃Sb₃Zn₂O₁₄ (RE = La, Pr, Nd, Sm, Eu, Gd) is a series of novel pyrochlore-related materials with 2D Kagome lattices formed by RE³⁺ and Sb⁵⁺. The rare earth is the only magnetic ion in the structure; this family is therefore an archetype for exploring magnetic frustration on a 2D Kagome lattice.

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Hyun, S., and S. Torquato. "Optimal and Manufacturable Two-dimensional, Kagomé-like Cellular Solids." Journal of Materials Research 17, no. 1 (January 2002): 137–44. http://dx.doi.org/10.1557/jmr.2002.0021.

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We used the topology optimization technique to obtain two-dimensional, isotropic cellular solids with optimal effective elastic moduli and effective conductivity. The overall aim was to obtain the best (simplest) manufacturable structures for these effective properties, i.e., single-length-scale structures. Three different but simple periodic structures arose due to the imposed geometric mirror symmetries: lattices with triangular-like cells, hexagonal-like cells, or Kagomé-like cells. As a general rule, the structures with the Kagomé-like cells provided the best performance over a wide range of densities, i.e., for 0 ≰ ф <0.6, where ф is the solid volume fraction (density). At high densities (ф > 0.6), Kagome-like structures were no longer possible, and lattices with hexagonal-like or triangular-like cells provide virtually the same optimal performance. The Kagomé-like structures were found to be a new class of cellular solids with many useful features, including desirable transport and elastic properties, heat-dissipation characteristics, improved mechanical strength, and ease of fabrication.

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Zhu, Xing, Hong Wang, and Li-Xian Zheng. "Defect solitons in kagome optical lattices." Optics Express 18, no. 20 (September 15, 2010): 20786. http://dx.doi.org/10.1364/oe.18.020786.

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Kassan-Ogly, Felix A., B. N. Filippov, V. V. Men’shenin, Akai K. Murtazaev, M. K. Ramazanov, and M. K. Badiev. "Frustrations and Phase Transitions in Ising Model on 2D Lattices." Solid State Phenomena 168-169 (December 2010): 435–38. http://dx.doi.org/10.4028/www.scientific.net/ssp.168-169.435.

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The problem of frustrations and phase transition appearance or suppression is studied on the base of exact analytical solutions for maximum eigenvalue of Kramers-Wannier transfer matrix in the Ising model on a square lattice [1], a triangular and honeycomb lattices [2], and kagome lattice [3] with allowance for the interactions between nearest J is studied. We also studied these phenomena by the numerical “replica Monte Carlo method”, taking also into account the interactions between next-nearest neighbors J'.

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Kerdelhué, Philippe, and Jimena Royo-Letelier. "On the low lying spectrum of the magnetic Schrödinger operator with kagome periodicity." Reviews in Mathematical Physics 26, no. 10 (November 2014): 1450020. http://dx.doi.org/10.1142/s0129055x14500202.

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In a semi-classical regime, we study a periodic magnetic Schrödinger operator in ℝ2. This is inspired by recent experiments on artificial magnetism with ultra cold atoms in optical lattices, and by the new interest for the operator on the hexagonal lattice describing the behavior of an electron in a graphene sheet. We first review some results for the square (Harper), triangular and hexagonal lattices. Then, we study the case when the periodicity is given by the kagome lattice considered by Hou. Following the techniques introduced by Helffer–Sjöstrand and Carlsson, we reduce this problem to the study of a discrete operator on ℓ2(ℤ2;ℂ3) and a pseudo-differential operator on L2(ℝ;ℂ3), which keep the symmetries of the kagome lattice. We estimate the coefficients of these operators in the case of a weak constant magnetic field. Plotting the spectrum for rational values of the magnetic flux divided by 2πh where h is the semi-classical parameter, we obtain a picture similar to Hofstadter's butterfly. We study the properties of this picture and prove the symmetries of the spectrum and the existence of flat bands, which do not occur in the case of the three previous models.

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Li, Zhenhua, Chuanfu Cheng, Hanping Liu, Dawei Li, Shicai Xu, Huilan Liu, Junye Zhang, and Suzhen Zhang. "Experimental generation of Kagome lattices using metasurface of integrated convex lens." Chinese Optics Letters 18, no. 1 (2020): 012201. http://dx.doi.org/10.3788/col202018.012201.

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Wang, Peng, Xue Jiang, Jun Hu, Biao Wang, Tingwei Zhou, Hongkuan Yuan, and Jijun Zhao. "Robust spin manipulation in 2D organometallic Kagome lattices: a first-principles study." Physical Chemistry Chemical Physics 22, no. 19 (2020): 11045–52. http://dx.doi.org/10.1039/d0cp00742k.

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Dissertations / Theses on the topic "Kagome lattices"

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Wulferding, Dietrich [Verfasser], and Peter [Akademischer Betreuer] Lemmens. "Light scattering in antiferromagnets with competing interactions - from spin chains to kagome lattices / Dietrich Wulferding ; Betreuer: Peter Lemmens." Braunschweig : Technische Universität Braunschweig, 2013. http://d-nb.info/1175822426/34.

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Leung, Anthony Chi Hin. "Actuation properties of kagome lattice structures." Thesis, University of Cambridge, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613328.

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Iqbal, Yasir. "Liquides de spin dans les modèles antiferromagnétiques quantiques sur réseaux bi-dimensionnels frustrés." Phd thesis, Université Paul Sabatier - Toulouse III, 2012. http://tel.archives-ouvertes.fr/tel-00752096.

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La recherche de phases magnétiques exotiques de la matière qui fondent même à T=0 uniquement sous l'action des fluctuations quantiques a été long et ardu, à la fois théoriquement et expérimentalement. La percée est venue récemment avec la découverte de l'Herbertsmithite, un composé formant un réseau kagome parfait avec des moments magnétiques de spin-1/2. Des expériences pionnières, mêlant des mesures de NMR, µSR et de diffusion de neutrons, ont montré une absence totale de gel ou d'ordre des moments magnétiques de spin, fournissant ainsi une forte signature d'une phase paramgnétique quantique. Théoriquement, l'Herbertsmithite est extrêmement bien modélisé par le modèle de Heisenberg quantique antiferromagnétique pour des spins-1/2 sur le réseau kagome, problème qui n'a pas été résolu jusqu'à présent. Plusieurs méthodes approximatives numériques et analytiques ont donné différents états fondamentaux, allant des liquides de spins Z2 gappés et un liquide de spins exotique algébrique U(1) de Dirac aux liquides de spins chiraux et les cristaux à liaisons de valence. Dans cette thèse, le problème est traité dans le cadre d'une approche particule-esclave fermionique, à savoir le formalisme des fermions de Schwinger SU(2). Il est conclu qu'un liquide de spins sans gap algébrique de Dirac a l'énergie variationnelle la plus basse et peut en fait constituer un vrai état fondamental physique de liquide de spins. Une implémentation sophistiquée de méthodes numériques de pointes comme le Monte-Carlo variationnel, le Monte-Carlo fonctions de Green et l'application de pas Lanczos dans un schéma variationnel ont été utilisés. Il est montré que contrairement à la croyance habituelle, le liquide de spins de Dirac U(1) projeté en "2+1" dimensions est remarquablement robuste par rapport à une large classe de perturbations, incluant les liquides de spins topologiques Z2 et les cristaux à liaisons de valence. De plus, l'application de deux pas Lanczos sur la fonction d'onde du liquide de spins de Dirac U(1) montre que son énergie est compétitive avec celles proposées pour les liquides de spins topologiques Z2. Ce résultat, combiné avec les indications expérimentales qui pointent vers un liquide de spins sans gap pour l'Herbertsmithite, appuie l'affirmation que le vrai état fondamental de ce modèle est en fait un liquide de spins algébrique de Dirac.

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Tan, Zhiming Darren. "Frustrated magnetism in the extended kagome lattice." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:151fb421-198b-44b5-9f0d-8b35333f6450.

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The extended kagome lattice, composed of alternating kagome and triangular layers, provides a novel geometry for frustrated magnetism. In this thesis, we study the properties of Heisenberg spins with nearest-neighbour antiferromagnetic interactions on this lattice. In common with many other models of frustrated magnets, this system has highly degenerate classical ground states. It is set apart from other examples, however, by the strong interlayer correlations between triangular layer spins. We study the implications of such correlations in both the statics and dynamics. We characterise classical ground states using a flux picture for a single layer of kagome spins, a theoretical description that sets geometrical bounds on correlations. We quantify the divergent but sub-extensive ground state degeneracy by a Maxwellian counting argument, and verify this calculation by analysing the energy eigenvalues of numerical ground states. We explore the ground state connectedness but do not reach firm conclusions on this issue. We use the self-consistent Gaussian approximation (SCGA) to calculate static spin correlations at finite temperature. The results of these calculations agree well with elastic neutron scattering experiments. We derive an expression for the effective interlayer interaction between kagome spins by integrating out the triangular lattice spins. We use linear spinwave theory to compute the spin excitation spectrum numerically. This shows encouraging similarity with inelastic neutron scattering data on a single-crystal YBaCo$_4$O$_7$ sample, for a wide range of wavevector and frequency. This agreement shows that our spin model is a reasonable description of the physics, and suggests that this numerical technique might be useful for other geometrically frustrated magnets. We study the dynamics analytically using the stochastic SCGA recently developed for the pyrochlore lattice. For technical reasons, we apply this technique on a related model, the stacked kagome lattice, rather than on the extended kagome lattice itself. From this we find slow relaxation at low temperature, with a rate ~ T² compared to the faster ~ T scaling for the pyrochlore. Strikingly, in simulations of the dynamics on the extended kagome lattice by numerical integration of the semiclassical equations of motion, we find two different relaxation rates. Kagome layer spins relax more quickly than the triangular layer spins, having ~ T.

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Fujii, Yutaka. "NMR Study on Organic Radical Antiferromagnets on Kagomé Lattice and Distorted Kagomé Lattice." Kyoto University, 2001. http://hdl.handle.net/2433/151581.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(人間・環境学)
甲第8668号
人博第111号
12||113(吉田南総合図書館)
新制||人||27(附属図書館)
UT51-2001-A756
京都大学大学院人間・環境学研究科文化・地域環境学専攻
(主査)教授後藤喬雄, 教授前川覚, 教授冨田博之
学位規則第4条第1項該当

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O'Brien, Aroon. "Charge degrees of freedom on the kagome lattice." Doctoral thesis, Universitätsbibliothek Chemnitz, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-71860.

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Within condensed matter physics, systems with strong electronic correlations give rise to fascinating phenomena which characteristically require a physical description beyond a one-electron theory, such as high temperature superconductivity, or Mott metal-insulator transitions. In this thesis, a class of strongly correlated electron systems is considered. These systems exhibit fractionally charged excitations with charge +e/2 or -e/2 in two dimensions (2D) and three dimensions (3D), a consequence of both strong correlations and the geometrical frustration of the interactions on the underlying lattices. Such geometrically frustrated systems are typically characterized by a high density of low-lying excitations, leading to various interesting physical effects. This thesis constitutes a study of a model of spinless fermions on the geometrically frustrated kagome lattice. Focus is given in particular to the regime in which nearest-neighbour repulsions V are large in comparison with hopping t between neighbouring sites, the regime in which excitations with fractional charge occur. In the classical limit t = 0, the geometric frustration results in a macroscopically large ground-state degeneracy. This degeneracy is lifted by quantum fluctuations. A low-energy effective Hamiltonian is derived for the spinless fermion model for the case of 1/3 filling in the regime where |t| << V . In this limit, the effective Hamiltonian is given by ring-exchange of order ~ t^3/V^2, lifting the degeneracy. The effective model is shown to be equivalent to a corresponding hard-core bosonic model due to a gauge invariance which removes the fermionic sign problem. The model is furthermore mapped directly to a Quantum Dimer model on the hexagonal lattice. Through the mapping it is determined that the kagome lattice model exhibits plaquette order in the ground state and also that fractional charges within the model are linearly confined. Subsequently a doped version of the effective model is studied, for the case where exactly one spinless fermion is added or subtracted from the system at 1/3 filling. The sign of the newly introduced hopping term is shown to be removable due to a gauge invariance for the case of hole doping. This gauge invariance is a direct result of the bipartite nature of the hole hopping and is confirmed numerically in spectral density calculations. For further understanding of the low-energy physics, a derivation of the model gauge field theory is presented and discussed in relation to the confining quantum electrodynamic in two dimensions. Exact diagonalization calculations illustrate the nature of the fractional charge confinement in terms of the string tension between a bound pair of defects. The calculations employ topological symmetries that exist for the manifold of ground-state configurations. Dynamical calculations of the spectral densities are considered for the full spinless fermion Hamiltonian and compared in the strongly correlated regime with the doped effective Hamiltonian. Calculations for the effective Hamiltonian are then presented for the strongly correlated regime where |t| << V . In the limit g << |t|, the fractional charges are shown to be effectively free in the context of the finite clusters studied. Prominent features of the spectral densities at the Gamma point for the hole and particle contributions are attributed to approximate eigenfunctions of the spinless fermion Hamiltonian in this limit. This is confirmed through an analytical derivation. The case of g ~ t is then considered, as in this case the confinement of the fractional charges is observable in the spectral densities calculated for finite clusters. The bound states for the effectively confined defect pair are qualitatively estimated through the solution of the time-independent Schroedinger equation for a potential which scales linearly with g. The double-peaked feature of spectral density calculations over a range of g values can thus be interpreted as a signature of the confinement of the fractionally charged defect pair. Furthermore, the metal-insulator transition for the effective Hamiltonian is studied for both t > 0 and t < 0. Exact diagonalization calculations are found to be consistent with the predictions of the effective model. Further calculations confirm that the sign of t is rendered inconsequential due to the gauge invariance for g in the regime |t| << V . The charge-order melting metal-insulator transition is studied through density-matrix renormalization group calculations. The opening of the energy gap is found to differ for the two signs of t, reflecting the difference in the band structure at the Fermi level in each case. The qualitative nature of transition in each case is discussed. As a step towards a realization of the model in experiment, density-density correlation functions are introduced and such a calculation is shown for the plaquette phase for the effective model Hamiltonian at 1/3 filling in the absence of defects. Finally, the open problem of statistics of the fractional charges is discussed.

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Roychowdhury, Krishanu. "Aspects of many-body systems on a kagome lattice." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-193552.

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Strongly correlated systems on geometrically frustrated lattices can stabilize a large number of interesting phases that includes a wide array of novel Mott insulators in both bosonic and electronic systems. Charge fluctuations in a Mott insulator are suppressed due to strong mutual interaction among the particles. The presence of frustration is of particular importance as the physics it offers is often rich, unexpectedly complicated, and continues to raise many open questions. The thesis elucidates some of these issues on a kagome lattice where strong interactions among the particles in the Mott phase impose non-trivial local constraints depending on the filling fraction on the lattice. These Mott insulators, in addition to featuring unusual magnetic and/or charge ordering, can also harbor topologically ordered states of quantum matter, e.g., resonating valence bond liquids realized in certain quantum dimer models on non-bipartite lattices. The dimer models can be regarded as low-energy effective theories for different types of bosonic models in the strong-coupling limit. Exploring this connection is a central theme of this thesis with the aim of realizing novel strongly correlated ground states. Past studies of these models have revealed the existence of various ordered and disordered phases with distinct signatures. Among these low-energy phases, the presence of a stable topological liquid at a particular point, known as Rokhsar-Kivelson point, in the phase diagram is notable. The classical versions of the dimer model are also known to have garnered a vast interest in various fields ranging from problems of pure mathematical origin to ones in physical chemistry as well as statistical physics. Pioneered by Kasteleyn, several analytical works came forward to exactly calculate the partition function of the problem from which other physical observables can be derived. Classical numerical methods are extensively applied to these models to verify the analytical predictions. We introduce a new classical algorithm here to compute the correlation functions of a classical dimer model on a square (bipartite) and a triangular (non-bipartite) lattice based on a tensor network construction. The method, called tensor network renormalization group, turns out to be a powerful tool for simulating short-ranged gapped systems as inferred from our results benchmarked against the classical Monte-Carlo technique and compared with past analytical studies. One should note that the quantum dimer model at the Rokhsar-Kivelson point can also be described as an infinite temperature canonical ensemble of classical dimers because of the particular structure of the ground state which is an equal weight superposition in the configuration manifold. The geometry of the lattice plays a pivotal role in deciding the nature of the phases that arise in the dimer models. Many physical properties of the dimer liquid phase can be extracted in the simple classical setting which certainly allows for a deep understanding of the classical models to be developed. The liquid phase is gapped on non-bipartite lattices and gapless on bipartite lattices, which is reflected in the decay of correlation functions with spatial distances. In general on non-bipartite lattices, the topological nature of the dimer liquid is characterized by a Z2 topological order which survives even when the model is perturbed away from the Rokhsar-Kivelson point. Stability of this liquid phase not only depends on the lattice geometries but notably on dimer concentrations also. In this context, we focus on a particular variant of the dimer model on a triangular lattice which is known as the quantum fully packed loop model. The model is composed of nonintersecting closed loops made of dimers and governed by the same Hamiltonian as the quantum dimer model. The loop model provides an effective low-energy description of a strongly correlated bosonic system at 1/3 filling on the kagome lattice. The corresponding Bose-Hubbard Hamiltonian consists of nearest-neighbor hopping and all possible repulsive interactions within a hexagonal plaquette. Conspicuous features of the zero-temperature phase diagram for this model include (i) presence of a stable Z2 liquid even without any Rokhsar-Kivelson potential term (in distinction to the standard quantum dimer model), and (ii) an unconventional phase transition from the liquid phase to a novel crystalline phase that has nematic order (dubbed lattice nematic). For a deeper understanding of the physics, a mapping to an Ising gauge theory is presented. The gauge theoretic description provides a useful way to predict the nature of the quantum phase transition to lie in the O(3) universality class. Finally a fermionic model at the same 1/3 filling is considered in which the ground state exhibits a number of exotic local orderings resulting from the spin-charge interplay of electrons. The Hamiltonian comprises nearest-neighbor hopping, strong on-site Coulomb interaction, and repulsive interaction terms only between nearest-neighbors. In the strong correlation limit, this fermionic problem maps to a two-color fully packed loop model – a model in which the loop segments carry an additional quantum number as color on a honeycomb lattice. The effective theory is governed by coherent three-particle ring exchanges and nearest-neighbor antiferromagnetic spin exchanges. The competition between these two leads to a phase diagram composed of a novel plaquette ordered state (known as the plaquette phase) that undergoes phase transition to a new kind of charge ordered state which we call a short loop phase. From our numerical analysis, we conclude that the plaquette phase features an unusual antiferromagnetic order with gapless spin excitations while the charge-ordered state is subjugated by spin fluctuations of localized electrons arranged in small hexagonal loops on the kagome lattice.

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Pinto, Dias Daniela. "Topological properties of flat bands in generalized Kagome lattice materials." Thesis, KTH, Fysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-301294.

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Topological insulators are electronic materials that behave like an ordinary insulator in their bulk but have robust conducting states on their edge. Besides, in some materials the band structure presents completely flat bands, a special feature leading to strong interactions effects. In this thesis we present a study of the edge states of three particular two-dimensional models presenting flat bands: the honeycomb-Kagome, the $\alpha$--graphyne and a ligand decorated honeycomb-Kagome lattice models. We extend earlier work done on these lattice models by focusing on the topological nature of the edge states involving flat bands. We start by giving a review of the band structure theory and the tight-binding approximation. We then present several main topics in two-dimensional topological insulators such as the notion of topological invariants, the Kane-Mele model and the bulk-edge correspondence. Using these theoretical concepts we study the band structure of these lattices firstly without taking into account the spin and spin-orbit interations. We finally add these interactions to get their bulk band structures as well as the edge states. We observe how these spin-orbit interactions relieve degeneracies and allow for the emergence of edge states of topological nature. Since the lattices studied have an arrangement based on the honeycomb-Kagome lattice, two-dimensional materials having the structures of these lattices can be designed assembling metal ions and organic ligands. Therefore the results obtained could be used as a first hint to create new two-dimensional materials presenting topological properties.
Topologiska isolatorer är elektroniska material som uppför sig som en vanlig isolator i sin bulk men har robusta ledande stater på kanten. Dessutom presenterar bandstrukturen i vissa material helt platta band, en speciell egenskap som leder till starka interaktionseffekter. I denna avhandling presenterar vi en studie av kanttillstånden för tre speciella tvådimensionella modeller som presenterar platta band: bikakan-Kagome, $\alpha$-grafynen och en liganddekorerad honungskaka-Kagome modeller. Vi utökar tidigare arbete med dessa gittermodeller genom att fokusera på den topologiska karaktären hos kanttillstånd som innefattar platta band. Vi börjar med att ge en genomgång av bandstruktursteorin och den tätt bindande approximationen. Vi presenterar sedan flera huvudämnen i tvådimensionella topologiska isolatorer såsom begreppet topologiska invarianter, Kane-Mele modellen och bulk-kant korrespondensen. Med hjälp av dessa teoretiska begrepp studerar vi bandstrukturen för dessa gitter först utan att ta hänsyn till spinnen och spinnsorbital interaktioner. Vi lägger sedan till dessa interaktioner för att få sina bulkbandstrukturer såväl som kanttillstånden. Vi observerar hur dessa spinnsorbital interaktioner lindrar degenerationer och möjliggör uppkomsten av kanttillstånd av topologisk naturen. Eftersom de undersökta gitterna har ett arrangemang baserat på honungskaka-Kagome gitteren, kan tvådimensionella material med strukturerna hos dessa gitter utformas genom att montera metalljoner och organiska ligander. Därför kan de erhållna resultaten användas som en första ledtråd för att skapa nya tvådimensionella material med topologiska egenskaper.

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Silva, Junior José Luiz Ferreira da. "Efeito Kondo e magnetismo em uma rede Kagome." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2012. http://hdl.handle.net/10183/53142.

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Neste trabalho estudamos o modelo da rede de Kondo em uma rede kagome, buscando uma maior compreensão dos efeitos da frustração geométrica em sistemas de férmions pesados. Para tanto, fizemos uma aproximação de campo médio no hamiltoniano do sistema que serve para todas as fases do sistema. Analisamos inicialmente o caso não magnético. Obtemos neste limite as energias eletrônicas e as funções de Green necessárias ao cálculo numérico autoconsistente das ocupações e do parâmetro de Kondo. Os resultados encontrados estão em concordância qualitativa com trabalhos publicados em outras geometrias. A seguir analisamos o caso magnético, onde introduzimos uma aproximação suplementar, a qual é compatível com a de campo médio já considerada e, em princípio, existente apenas em sistemas com frustração geométrica. Realizamos cálculos autoconsistentes através de somas sobre as frequências de Matsubara. Os resultados mostram que não há coexistência entre ordem magnética e efeito Kondo, além de haver a supressão do antiferromagnetismo com o aumento de temperatura e variações no preenchimento de bandas.
In this work we study the Kondo Lattice model for the kagome lattice, in order to understand better the effects of geometrical frustration in heavy-fermion systems. In this context, we consider a mean field scheme valid for all the system’s phases. Firstly, we analyzed the nonmagnetic case. In this approximation the electron energies and spectral functions are reachable, then we use the density of states to calculate the occupations selfconsistently. Our results are qualitatively compared with previous works in other geometries. In the second part we introduce an approximation for magnestism, which takes into account the mean field scheme considered and the presence of geometrical frustration. Self-consistent calculations are done through the frequencies summation method. Our results show that the magnetism is supressed when the temperature is increased or the band filling deviates from half-filling. Besides, the coexistence of magnetic order and Kondo effect is not observable.

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Fong, Manson Cheuk-Man. "Heisenberg model with spin anisotropy on the Kagomé lattice /." View abstract or full-text, 2008. http://library.ust.hk/cgi/db/thesis.pl?PHYS%202008%20ZFONG.

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Book chapters on the topic "Kagome lattices"

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Ishizuka, Hiroaki. "Anomalous Hall Insulator in Kagome Ice." In Magnetism and Transport Phenomena in Spin-Charge Coupled Systems on Frustrated Lattices, 79–91. Tokyo: Springer Japan, 2015. http://dx.doi.org/10.1007/978-4-431-55663-3_6.

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Ishizuka, Hiroaki. "Thermally-Induced Phases on a Kagome Lattice." In Magnetism and Transport Phenomena in Spin-Charge Coupled Systems on Frustrated Lattices, 65–77. Tokyo: Springer Japan, 2015. http://dx.doi.org/10.1007/978-4-431-55663-3_5.

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Conference papers on the topic "Kagome lattices"

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Phani, A. Srikantha, and Norman A. Fleck. "Elastic Boundary Layers in Two-Dimensional Isotropic Lattices." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-35234.

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The phenomenon of elastic boundary layers under quasistatic loading is investigated using the Floquet-Bloch formalism for two-dimensional, isotropic, periodic lattices. The elastic boundary layer is a region of localised elastic deformation, confined to the free-edge of a lattice. Boundary layer phenomena in three isotropic lattice topologies are investigated: the semi-regular Kagome lattice, the regular hexagonal lattice and the regular fully-triangulated lattice. The boundary layer depth is on the order of the strut length for the hexagonal and the fully-triangulated lattices. For the Kagome lattice, the depth of boundary layer scales inversely with the relative density. Thus, the boundary layer in a Kagome lattice of low relative density spans many cells.

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Chern, Gia-Wei, and Avadh Saxena. "PT-symmetry in kagome photonic lattices." In Active Photonic Platforms IX, edited by Ganapathi S. Subramania and Stavroula Foteinopoulou. SPIE, 2017. http://dx.doi.org/10.1117/12.2274503.

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Mejía-Cortés, Cristian, and Rodrigo Vicencio. "Image transmission in Kagome photonic lattices." In Bragg Gratings, Photosensitivity, and Poling in Glass Waveguides. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/bgpp.2014.jtu3a.32.

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Saxena, Avadh, and Gia-Wei Chern. "PT-symmetry and kagome lattices (Conference Presentation)." In Active Photonic Materials VIII, edited by Ganapathi S. Subramania and Stavroula Foteinopoulou. SPIE, 2016. http://dx.doi.org/10.1117/12.2237920.

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Bird, James W., Matthew J. Santer, and Jonathan F. Morrison. "Adaptive Kagome Lattices for Near Wall Turbulence Suppression." In 23rd AIAA/AHS Adaptive Structures Conference. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2015. http://dx.doi.org/10.2514/6.2015-0270.

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Ni, Xiang, Andrea Alù, and Alexander B. Khanikaev. "Topological edge states of distorted photonic Kagome lattices." In Active Photonic Platforms IX, edited by Ganapathi S. Subramania and Stavroula Foteinopoulou. SPIE, 2017. http://dx.doi.org/10.1117/12.2273938.

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Schaeffer, Marshall D., and Massimo Ruzzene. "Wave propagation in 2D magneto-elastic kagome lattices." In SPIE Smart Structures and Materials + Nondestructive Evaluation and Health Monitoring, edited by Tribikram Kundu. SPIE, 2014. http://dx.doi.org/10.1117/12.2045064.

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Zong, Yuanyuan, Shiqiang Xia, Yi Hu, Daohong Song, Liqin Tang, and Zhigang Chen. "Observation of Localized Flat-band States and Diffraction-Free Image Transmission in Kagome Photonic Lattices." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/cleo_si.2016.sm3r.2.

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du Pasquier, Cosima, Pascal Koller, Tino Stankovic, and Kristina Shea. "Computational Design of Active Lattice Structures for 4D Printed Pneumatic Shape Morphing." In ASME 2019 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/detc2019-97775.

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Abstract With advances in 3D printing and digital fabrication an opportunity is presented to realize highly customized designs whose shape can change and adapt to facilitate their functionality. A computational design method to determine the configuration of 2D pneumatic shape morphing lattices using a direct search method is implemented and assessed. The method is tested using a Kagome unit cell lattice structure, which is particularly well suited for shape morphing. To achieve shape change, beams are replaced by linear actuators such as those found in pneumatic 4D printing, whose number and placement are optimized to replicate a given target shape. The actuator placement and deformation accuracy are given for four main curvature changes: linear, convex, concave and the transition from one to the other. The results are assessed in terms accuracy of deformation and computational effort. It is shown that the method proposed produces structures that can replicate complex shape changes within 1% of the desired shape. Reducing the number of actuators for robustness purposes is shown to affect the results minimally.

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Leung, Anthony, Digby Symons, and Simon Guest. "Actuation of Kagome Lattice Structures." In 45th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics & Materials Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2004. http://dx.doi.org/10.2514/6.2004-1525.

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Reports on the topic "Kagome lattices"

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Saxena, Avadh. PT-Symmetric Kagome Lattices and Localization. Office of Scientific and Technical Information (OSTI), June 2017. http://dx.doi.org/10.2172/1363733.

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