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We show that the bulk-boundary correspondence for topological insulators can be modified in the presence of non-Hermiticity. We consider a one-dimensional tight-binding model with gain and loss as well as long-range hopping. The system is…

Quantum Physics · Physics 2016-04-04 Tony E. Lee

Recently, antiferromagnetic (AF) materials have attracted rapid attention, because they are considered as outstanding candidates to replace the widely used ferromagnets in the next generation of spintronics. We propose a magnetoresistance…

Mesoscale and Nanoscale Physics · Physics 2025-09-05 Wei-Tao Lu , Qing-Feng Sun

We analyse the topological transition and localization evolution of disordered two dimensional systems with non trivial topology based on bipartite lattices. Chern insulators with broken time reversal symmetry show non standard behavior for…

Mesoscale and Nanoscale Physics · Physics 2015-09-03 Eduardo V. Castro , M. Pilar López-Sancho , María A. H. Vozmediano

The Hofstadter model is a simple yet powerful Hamiltonian to study quantum Hall physics in a lattice system, manifesting its essential topological states. Lattice dimerization in the Hofstadter model opens an energy gap at half filling.…

Mesoscale and Nanoscale Physics · Physics 2015-11-30 Alexander Lau , Carmine Ortix , Jeroen van den Brink

Using first principles methods, we investigate topological phase transitions as a function of exchange field in a Bi(111) bilayer. Evaluation of the spin Chern number for different magnitudes of the exchange field reveals that when the time…

Materials Science · Physics 2013-08-22 Hongbin Zhang , Frank Freimuth , Gustav Bihlmayer , Stefan Blügel , Yuriy Mokrousov

Recently, it has been shown how topological phases of matter with crystalline symmetry and $U(1)$ charge conservation can be partially characterized by a set of many-body invariants, the discrete shift $\mathscr{S}_{\text{o}}$ and electric…

Strongly Correlated Electrons · Physics 2025-02-28 Yuxuan Zhang , Maissam Barkeshli

As first demonstrated by the characterization of the quantum Hall effect by the Chern number, topology provides a guiding principle to realize robust properties of condensed matter systems immune to the existence of disorder. The…

Mesoscale and Nanoscale Physics · Physics 2023-08-01 Kazuki Sone , Motohiko Ezawa , Yuto Ashida , Nobuyuki Yoshioka , Takahiro Sagawa

We show that the Z$_2$ invariant, which classifies the topological properties of time reversal invariant insulators, has deep relationship with the global anomaly. Although the second Chern number is the basic topological invariant…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 T. Fukui , T. Fujiwara , Y. Hatsugai

Three-dimensional topological (crystalline) insulators are materials with an insulating bulk, but conducting surface states which are topologically protected by time-reversal (or spatial) symmetries. Here, we extend the notion of…

Mesoscale and Nanoscale Physics · Physics 2018-06-05 Frank Schindler , Ashley M. Cook , Maia G. Vergniory , Zhijun Wang , Stuart S. P. Parkin , B. Andrei Bernevig , Titus Neupert

We investigate a new class of topological antiferromagnetic (AF) Chern insulators driven by electronic interactions in two-dimensional systems without inversion symmetry. Despite the absence of a net magnetization, AF Chern insulators…

Strongly Correlated Electrons · Physics 2018-04-17 Kun Jiang , Sen Zhou , Xi Dai , Ziqiang Wang

One of the most important practical hallmarks of topological matter is the presence of topologically protected, exponentially localised edge states at interfaces of regions characterised by unequal topological invariants. Here, we show that…

Mesoscale and Nanoscale Physics · Physics 2024-01-01 Suraj S. Hegde , Toni Ehmcke , Tobias Meng

The realization and detection of topological phases with ultracold atomic gases is at the frontier of current theoretical and experimental research. Here, we identify cold atoms in optical ladders subjected to synthetic magnetic fields as…

Quantum Gases · Physics 2015-06-16 Dario Hügel , Belén Paredes

We study non-interacting electrons in disordered one-dimensional materials which exhibit a spectral gap, in each of the ten Altland-Zirnbauer symmetry classes. We define an appropriate topology on the space of Hamiltonians so that the…

Mathematical Physics · Physics 2023-07-04 Jui-Hui Chung , Jacob Shapiro

We theoretically introduce a quasi-1D magnetic heterostructure of alternating 2D topological and normal insulator strips. Its low-energy physics is governed by a hybrid Hamiltonian intertwining the Su-Schrieffer-Heeger and Shockley models,…

Mesoscale and Nanoscale Physics · Physics 2026-04-03 Z. Z. Alisultanov

Polaritonic lattice configurations in dimensions $D=2$ are used as simulators of topological phases, based on symmetry class A Hamiltonians. Numerical and topological studies are performed in order to characterise the bulk topology of…

Mesoscale and Nanoscale Physics · Physics 2023-11-01 Konstantin Rips

We complete a classification of topological phases and their topological defects in crystalline insulators and superconductors. We consider topological phases and defects described by non-interacting Bloch and Bogoliubov de Gennes…

Mesoscale and Nanoscale Physics · Physics 2014-10-15 Ken Shiozaki , Masatoshi Sato

Symmetry-protected topological phases of matter have challenged our understanding of condensed matter systems and harbour exotic phenomena promising to address major technological challenges. Considerable understanding of these phases of…

Strongly Correlated Electrons · Physics 2022-11-11 Ashley M. Cook , Joel E. Moore

Topological Insulators are a novel state of matter where spectral bands are characterized by quantized topological invariants. This unique quantized non-local property commonly manifests through exotic bulk phenomena and corresponding…

Mesoscale and Nanoscale Physics · Physics 2018-05-15 Mark Kremer , Ioannis Petrides , Eric Meyer , Matthias Heinrich , Oded Zilberberg , Alexander Szameit

We proof the existence of two different topological classes of low-energy k.p Hamiltonians for Chern insulators. Using the paradigmatic example of single-valley two-band models, we show that k.p Hamiltonians that we dub local have a…

Mesoscale and Nanoscale Physics · Physics 2015-03-26 Frank Kirtschig , Jeroen van den Brink , Carmine Ortix

Topological insulators exhibit gapless edge or surface states that are topologically protected by time-reversal symmetry. However, several promising candidates for topologically insulating materials (such as Bi$_2$Se$_3$ and HgTe) contain…

Mesoscale and Nanoscale Physics · Physics 2018-07-11 Arian Vezvaee , Antonio Russo , Sophia E. Economou , Edwin Barnes