arXiv: Strongly Correlated Electrons最新文献_第5页

arXiv: Strongly Correlated Electrons Pub Date : 2020-11-09 DOI: 10.13140/RG.2.2.21763.25127

W. Maimaiti

{"title":"Flatband generators","authors":"W. Maimaiti","doi":"10.13140/RG.2.2.21763.25127","DOIUrl":"https://doi.org/10.13140/RG.2.2.21763.25127","url":null,"abstract":"Flatbands (FBs) are dispersionless energy bands in the single-particle spectrum of a translational invariant tight-binding network. The FBs occur due to destructive interference, resulting in macroscopically degenerate eigenstates living in a finite number of unit cells, which are called compact localized states (CLSs). Such macroscopic degeneracy is in general highly sensitive to perturbations, such that even slight perturbation lifts the degeneracy and leads to various interesting physical phenomena. In this thesis, we develop an approach to identify and construct FB Hamiltonians in 1D, 2D Hermitian, and 1D non-Hermitian systems. First, we introduce a systematic classification of FB lattices by their CLS properties, and propose a scheme to generate tight-binding Hamiltonians having FBs with given CLS properties---a FB generator. Applying this FB generator to a 1D system, we identify all possible FB Hamiltonians of 1D lattices with arbitrary numbers of bands and CLS sizes. Extending the 1D approach, we establish a FB generator for 2D FB Hamiltonians that have CLSs occupying a maximum of four unit cells in a $2times2$ plaquette. Employing this approach in the non-Hermitiaon regime, we realize a FB generator for a 1D non-Hermitian lattice with two bands. Ultimately, we apply our methods to propose a tight-binding model that explains the spectral properties of a microwave photonic crystal. Our results and methods in this thesis further our understanding of the properties of FB lattices and their CLSs, provide more flexibility to design FB lattices in experiments, and open new avenues for future research.","PeriodicalId":8511,"journal":{"name":"arXiv: Strongly Correlated Electrons","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74892900","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 3

Light-induced switching of magnetic order in the anisotropic triangular-lattice Hubbard model 各向异性三角晶格Hubbard模型中磁序的光致开关

arXiv: Strongly Correlated Electrons Pub Date : 2020-11-09 DOI: 10.1103/PHYSREVB.103.L161106

Hayato Kobayashi, Ryo Fujiuchi, K. Sugimoto, Y. Ohta

引用次数: 2

Diffraction by multipoles in a 5d2 rhenium double perovskite 5d2双铼钙钛矿的多极衍射

arXiv: Strongly Correlated Electrons Pub Date : 2020-11-08 DOI: 10.1103/PHYSREVB.103.104429

S. Lovesey, D. Khalyavin, G. van der Laan, G. Nilsen

引用次数: 3

Orbital-order phase transition in Pr1−xCaxMnO3 probed by photovoltaics Pr1−xCaxMnO3的轨道序相变

arXiv: Strongly Correlated Electrons Pub Date : 2020-11-05 DOI: 10.1103/PhysRevB.103.235122

B. Kressdorf, T. Meyer, M. Ten Brink, C. Seick, S. Melles, N. Ottinger, T. Titze, H. Meer, A. Weisser, J. Hoffmann, S. Mathias, H. Ulrichs, D. Steil, M. Seibt, P. Blöchl, C. Jooss

{"title":"Orbital-order phase transition in \u0000Pr1−xCaxMnO3\u0000 probed by photovoltaics","authors":"B. Kressdorf, T. Meyer, M. Ten Brink, C. Seick, S. Melles, N. Ottinger, T. Titze, H. Meer, A. Weisser, J. Hoffmann, S. Mathias, H. Ulrichs, D. Steil, M. Seibt, P. Blöchl, C. Jooss","doi":"10.1103/PhysRevB.103.235122","DOIUrl":"https://doi.org/10.1103/PhysRevB.103.235122","url":null,"abstract":"A new phase diagram of $Pr_{1-x}Ca_xMnO_3$ for x $le$ 0.3 is derived that suggests a necessary revaluation of the phase diagram of other manganites in that doping region. Rather than an orbital ordered phase reaching up to high temperatures 850 K for x=0.1 and 950 K for x=0, we propose a loss of spontaneous order already near room temperature. Above this temperature, the phase is characterized by a finite orbital polarization and octahedral tilt pattern. The tilt pattern couples to the Jahn-Teller distortion and thus induces a remaining orbital order, which persists up to high temperatures, where the tilt order is lost as well. This explains the experimental observation of orbital order up to high temperatures. Anomalies at a temperature 220-260 K have been observed in epitaxial thin films of doping x=0.1 for photovoltaic effect, electric transport, magnetisation, optical and ultrafast transient pump probe studies. The onset of the polaron photovoltaic effect and the increase of the hot polaron relaxation time below $T_{OO}$ suggest a change in the orbital order. Finite-temperature simulations based on a tight-binding model with carefully adjusted parameters from first-principles calculations exhibit an orbital-order phase transition at $T_{OO} approx$ 300 K for x=0.1. This is consistent with the experimental observation of a change in temperature dependent lattice parameter for bulk samples of the same doping at 300 K for x=0.1 and 350 K for x=0, typical for a second order phase transition.","PeriodicalId":8511,"journal":{"name":"arXiv: Strongly Correlated Electrons","volume":"116 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80402738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Matrix product wave function of the ground state and elementary excitations in the spin-12 chain 自旋-12链中基态和基本激发的矩阵积波函数

arXiv: Strongly Correlated Electrons Pub Date : 2020-11-05 DOI: 10.1103/PHYSREVB.103.125157

Jintae Kim, Minsoo P. Kim, Pramod Padmanabhan, J. Han, Hyunyong Lee

引用次数: 0

Electron quasi-itinerancy intertwined with quantum order by disorder in pyrochlore iridate magnetism 焦绿石铱磁性中电子准巡回与量子有序交织在一起

arXiv: Strongly Correlated Electrons Pub Date : 2020-11-04 DOI: 10.1103/physrevresearch.2.043273

Gang Chen, Xiaoqun Wang

引用次数: 0

Weak topological insulating phases of hard-core-bosons on the honeycomb lattice 蜂窝晶格上硬核玻色子的弱拓扑绝缘相

arXiv: Strongly Correlated Electrons Pub Date : 2020-10-30 DOI: 10.21468/SCIPOSTPHYS.10.3.059

Amrita Ghosh, E. Grosfeld

引用次数: 5

Epitaxial stabilization of (111)-oriented frustrated quantum pyrochlore thin films (111)取向受挫量子焦绿石薄膜的外延稳定性

arXiv: Strongly Correlated Electrons Pub Date : 2020-10-30 DOI: 10.1063/5.0035702

Fangdi Wen, Tsung-Chi Wu, Xiaoran Liu, M. Terilli, M. Kareev, J. Chakhalian

引用次数: 1

Phase transitions between helices, vortices, and hedgehogs driven by spatial anisotropy in chiral magnets 手性磁体中空间各向异性驱动的螺旋、漩涡和刺猬之间的相变

arXiv: Strongly Correlated Electrons Pub Date : 2020-10-30 DOI: 10.1103/PHYSREVB.103.054427

K. Shimizu, S. Okumura, Y. Kato, Y. Motome

{"title":"Phase transitions between helices, vortices, and hedgehogs driven by spatial anisotropy in chiral magnets","authors":"K. Shimizu, S. Okumura, Y. Kato, Y. Motome","doi":"10.1103/PHYSREVB.103.054427","DOIUrl":"https://doi.org/10.1103/PHYSREVB.103.054427","url":null,"abstract":"Superpositions of spin helices can yield topological spin textures, such as two-dimensional vortices and skyrmions, and three-dimensional hedgehogs. Their topological nature and spatial dimensionality depend on the number and relative directions of the constituent helices. This allows mutual transformation between the topological spin textures by controlling the spatial anisotropy. Here we theoretically study the effect of anisotropy in the magnetic interactions for an effective spin model for chiral magnetic metals. By variational calculations for both cases with triple and quadruple superpositions, we find that the hedgehog lattices, which are stable in the isotropic case, are deformed by the anisotropy, and eventually changed into other spin textures with reduced dimension, such as helices and vortices. We also clarify the changes of topological properties by tracing the real-space positions of magnetic monopoles and antimonopoles as well as the emergent magnetic field generated by the noncoplanar spin textures. Our results suggest possible control of the topological spin textures, e.g., by uniaxial pressure and chemical substitution in chiral materials.","PeriodicalId":8511,"journal":{"name":"arXiv: Strongly Correlated Electrons","volume":"240 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72925695","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Quasi-flat-band physics in a two-leg ladder model and its relation to magic-angle twisted bilayer graphene 两腿阶梯模型中的准平带物理及其与魔角扭曲双层石墨烯的关系

arXiv: Strongly Correlated Electrons Pub Date : 2020-10-28 DOI: 10.1103/physrevb.102.155429

Yixuan Huang, P. Hosur, H. Pal

引用次数: 5