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Strong directional disorder in local magnetic moments coupled to a Chern insulator gives rise to topological phases that cannot be continuously connected to the clean limit and are therefore genuinely disorder-driven. We demonstrate this in…

Mesoscale and Nanoscale Physics · Physics 2026-02-17 Devesh Vaish , Michael Potthoff

Thermal noise can destroy topological insulators (TI). However we demonstrate how TIs can be made stable in dissipative systems. To that aim, we introduce the notion of band Liouvillian as the dissipative counterpart of band Hamiltonian,…

Mesoscale and Nanoscale Physics · Physics 2013-11-04 A. Rivas , O. Viyuela , M. A. Martin-Delgado

We survey various quantized bulk physical observables in two- and three-dimensional topological band insulators invariant under translational symmetry and crystallographic point group symmetries (PGS). In two-dimensional insulators, we show…

Mesoscale and Nanoscale Physics · Physics 2012-11-15 Chen Fang , Matthew J. Gilbert , B. Andrei Bernevig

Chern insulators are band insulators which exhibit a gap in the bulk and gapless excitations in the edge. Detection of Chern insulators is a serious challenge in cold atoms since the Hall transport measurements are technically unrealistic…

Mesoscale and Nanoscale Physics · Physics 2013-09-30 Xiong-Jun Liu , K. T. Law , T. K. Ng , Patrick A. Lee

The Chern index characterizes the topological phases of nonreciprocal photonic systems. Unlike in electronic systems, the photonic Chern number has no clear physical meaning, except that it determines the net number of unidirectional edge…

Optics · Physics 2019-03-06 Mário G. Silveirinha

Topological insulators are exotic material that possess conducting surface states protected by the topology of the system. They can be classified in terms of their properties under discrete symmetries and are characterized by topological…

Quantum Gases · Physics 2019-05-29 M. Mochol-Grzelak , A. Dauphin , A. Celi , M. Lewenstein

Local topological markers, topological invariants evaluated by local expectation values, are valuable for characterizing topological phases in materials lacking translation invariance. The Chern marker -- the Chern number expressed in terms…

Mesoscale and Nanoscale Physics · Physics 2023-01-11 Julia D. Hannukainen , Miguel F. Martinez , Jens H. Bardarson , Thomas Klein Kvorning

Topology has appeared in different physical contexts. The most prominent application is topologically protected edge transport in condensed matter physics. The Chern number, the topological invariant of gapped Bloch Hamiltonians, is an…

Mesoscale and Nanoscale Physics · Physics 2018-01-24 Thomas Fösel , Vittorio Peano , Florian Marquardt

The identification of the topological invariant of a topological system is crucial in experiments. However, due to the inherent non-Hermitian features, such determination is notably challenging in non-Hermitian systems. Here, we propose…

Mesoscale and Nanoscale Physics · Physics 2024-01-30 Hongfang Liu , Ming Lu , Shengdu Chai , Zhi-Qiang Zhang , Hua Jiang

Characteristic classes, which are abstract topological invariants associated with vector bundles, have become an important notion in modern physics with surprising real-world consequences. As a representative example, the incredible…

Mesoscale and Nanoscale Physics · Physics 2023-12-11 Cody Tipton , Elizabeth Coda , Davis Brown , Alyson Bittner , Jung Lee , Grayson Jorgenson , Tegan Emerson , Henry Kvinge

We derive the macroscopic charge and current densities of a Chern insulator initially occupying its electronic ground state as it responds to a finite-frequency electric field; we use a previously developed formalism based on microscopic…

Mesoscale and Nanoscale Physics · Physics 2025-01-28 Jason G. Kattan , Alistair H. Duff , J. E. Sipe

Chern insulators present a topological obstruction to a smooth gauge in their Bloch wave functions that prevents the construction of exponentially-localized Wannier functions - this makes the electric polarization ill-defined. Here, we show…

Mesoscale and Nanoscale Physics · Physics 2025-03-28 Sachin Vaidya , Mikael C. Rechtsman , Wladimir A. Benalcazar

The topology of quantum systems has become a topic of great interest since the discovery of topological insulators. However, as a hallmark of the topological insulators, the spin Chern number has not yet been experimentally detected. The…

The appearance of fractional Chern insulators in moir\'e systems can be rationalized by the presence of a fictitious magnetic field associated with the spatial texture of layer-resolved electronic wavefunctions. Here, we present a…

Mesoscale and Nanoscale Physics · Physics 2025-07-02 Kryštof Kolář , Kang Yang , Felix von Oppen , Christophe Mora

We show the existence of energies exhibiting dynamical delocalization in discrete 2D Chern insulators perturbed by a random potential in a general setting. Our proof exploits two main features of the model: jumps in the integer value of the…

Mathematical Physics · Physics 2026-05-07 Gianluca Panati , Constanza Rojas-Molina , Vincenzo Rossi

We evaluate the real-space second Chern number of four-dimensional Chern insulators using the kernel polynomial method. Our calculations are performed on a four-dimensional system with $30^4$ sites, and the numerical results agree well with…

Mesoscale and Nanoscale Physics · Physics 2026-02-04 Rui Chen , Bin Zhou

Impurities embedded in electronic systems induce bound states which under certain circumstances can hybridize and lead to impurity bands. Doping of insulators with impurities has been identified as a promising route towards engineering…

Mesoscale and Nanoscale Physics · Physics 2019-04-17 Emma L. Minarelli , Kim Pöyhönen , Gerwin A. R. van Dalum , Teemu Ojanen , Lars Fritz

The Chern-Hopf insulator is an unconventional three-dimensional topological insulator with a bulk gap and gapless boundary states without protection from global discrete symmetries. This study investigates its fate in the presence of…

Disordered Systems and Neural Networks · Physics 2025-05-13 Soumya Bera , Ivan Dutta , Roderich Moessner , Kush Saha

If an extensive partition in two dimensions yields a gapful entanglement spectrum of the reduced density matrix, the Berry curvature based on the corresponding entanglement eigenfunction defines the Chern number. We propose such an…

Mesoscale and Nanoscale Physics · Physics 2014-10-15 T. Fukui , Y. Hatsugai

The organization of the electrons in the ground state is classified by means of topological invariants, defined as global properties of the wavefunction. Here we address the Chern number of a two-dimensional insulator and we show that the…

Strongly Correlated Electrons · Physics 2012-01-23 Raffaello Bianco , Raffaele Resta