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The topological response to external perturbations is an effective probe to characterize different topological phases of matter. Besides the Hall conductance, the Hall viscosity is another example of such a response that measures how…

Mesoscale and Nanoscale Physics · Physics 2015-11-03 Hassan Shapourian , Taylor L. Hughes , Shinsei Ryu

Using recently developed tools from space-adiabatic perturbation theory, in particular the construction of a non-equilibrium almost stationary state, we give a new proof that the Kubo formula for the Hall conductivity remains valid beyond…

Mathematical Physics · Physics 2023-02-06 Giovanna Marcelli , Domenico Monaco

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

Integer and fractional Chern insulators exhibit a nonzero quantized anomalous Hall conductivity due to a spontaneous breaking of time reversal symmetry. To identify nontrivial topology in their time-reversal symmetric many-body spectra, we…

Strongly Correlated Electrons · Physics 2026-01-21 Axel Fünfhaus , Titus Neupert , Thilo Kopp , Roser Valentí

We report the theoretical discovery of a systematic scheme to produce topological flat bands (TFBs) with arbitrary Chern numbers. We find that generically a multi-orbital high Chern number TFB model can be constructed by considering…

Strongly Correlated Electrons · Physics 2013-01-01 Shuo Yang , Zheng-Cheng Gu , Kai Sun , S. Das Sarma

Chern number is a crucial invariant for characterizing topological feature of two-dimensional quantum systems. Real-space Chern number allows us to extract topological properties of systems without involving translational symmetry, and…

Quantum Physics · Physics 2024-11-04 Ling Lin , Yongguan Ke , Li Zhang , Chaohong Lee

In this work, we propose an exactly solvable two-dimensional lattice model of strongly correlated electrons that realizes a quantum anomalous Hall insulator with Chern number $\mathcal{C}=1$. First, we show that the interplay of ionic…

Strongly Correlated Electrons · Physics 2023-07-13 Marcin M. Wysokiński , Wojciech Brzezicki

We derive the topological Chern number of the integer quantum Hall effect in electrical conductivity, using Buot's superfield and lattice Weyl transform nonequilibrium quantum transport formalism. The method is naturally straightforward,…

Mesoscale and Nanoscale Physics · Physics 2021-03-23 Felix A. Buot

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

Lattice models forming bands with higher Chern number offer an intriguing possibility for new phases of matter with no analogue in continuum Landau levels. Here, we establish the existence of a number of new bulk insulating states at…

Strongly Correlated Electrons · Physics 2012-11-06 Zhao Liu , Emil J. Bergholtz , Heng Fan , Andreas M. Laeuchli

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

The observed robustly quantized Hall conductance in quantum Hall systems and Chern insulators (CI) have so far been understood in terms of the topology of isolated systems, which are not coupled to leads. It is assumed that the leads act as…

Mesoscale and Nanoscale Physics · Physics 2025-12-16 Satyam Sinha , Rekha Kumari , Junaid Majeed Bhat , Abhishek Dhar , R. Shankar

Studies on two-dimensional electron systems in a strong magnetic field first revealed the quantum Hall (QH) effect, a topological state of matter featuring a finite Chern number (C) and chiral edge states. Haldane later theorized that Chern…

Topological quantum numbers account for the precise quantization that occurs in the integer Hall effect. In this theory, Kubo's formula for the conductance acquires a topological interpretation in terms of Chern numbers and their…

Mathematical Physics · Physics 2007-05-23 J. E. Avron , D. Osadchy , R. Seiler

This paper is a survey of the $\mathbb{Z}_2$-valued invariant of topological insulators used in condensed matter physics. The $\mathbb{Z}$-valued topological invariant, which was originally called the TKNN invariant in physics, has now been…

Mathematical Physics · Physics 2016-12-28 Ralph M. Kaufmann , Dan Li , Birgit Wehefritz-Kaufmann

Band topology of anomalous quantum Hall insulators can be precisely addressed by computing Chern numbers of constituent non-degenerate bands that describe quantized, Abelian Berry flux through two-dimensional Brillouin zone. Can Chern…

We consider the visco-elastic response of the electronic degrees of freedom in 2D and 3D topological insulators (TI). Our primary focus is on the 2D Chern insulator which exhibits a bulk dissipationless viscosity analogous to the quantum…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Taylor L. Hughes , Robert G. Leigh , Eduardo Fradkin

The checkerboard lattice is a two-dimensional non-trivial structure usually seen as a planar version of the pyrochlore lattice. This geometry supports a two-band insulating electronic system with Chern topology induced by a complex hopping…

Mesoscale and Nanoscale Physics · Physics 2024-12-24 P. G. de Oliveira , A. S. T. Pires

As an important figure of merit for characterizing the quantized collective behaviors of the wavefunction, Chern number is the topological invariant of quantum Hall insulators. Chern number also identifies the topological properties of the…

In 2D semiconductors and insulators, the Chern number of the valence band Bloch state is an important quantity that has been linked to various material properties, such as the topological order. We elaborate that the opacity of 2D materials…

Strongly Correlated Electrons · Physics 2023-10-25 Paolo Molignini , Bastien Lapierre , R. Chitra , Wei Chen