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In theory of topological classification, the 2D topological superconductors without time reversal symmetry are characterized by Chern numbers. However, in reality, we find the Chern numbers can not reveal the whole properties of the…

Superconductivity · Physics 2022-03-04 Jinpeng Xiao , Qianglin Hu , Huiqiong Zeng , Xiaobing Luo

Chern numbers are gaining traction as they characterize topological phases in various physical systems. However, the resilience of the system topology to external perturbations makes it challenging to experimentally investigate transitions…

Quantum Physics · Physics 2022-11-28 Junghyun Lee , Keigo Arai , Huiliang Zhang , Mark J. H. Ku , Ronald L. Walsworth

Topological quantum phase transitions in superconductivity are discussed on two dimensional lattices. The main focus is on the Chern number for superconducting states. Each superconductivity is characterized by the Chern number, and the…

Superconductivity · Physics 2009-11-07 Yasuhiro Hatsugai , Shinsei Ryu

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

Amorphous systems have rapidly gained promise as novel platforms for topological matter. In this work we establish a scaling theory of amorphous topological phase transitions driven by the density of lattice points in two dimensions. By…

Mesoscale and Nanoscale Physics · Physics 2020-01-22 Isac Sahlberg , Alex Westström , Kim Pöyhönen , Teemu Ojanen

We discuss the Chern number spectrum of ultra-cold fermions in square optical lattices as a function of artificial magnetic, Zeeman and spin-orbit fields that can be tuned independently. We show the existence of topological quantum phase…

Quantum Gases · Physics 2019-05-01 Man Hon Yau , C. A. R. Sa de Melo

It is known that, in the thermodynamic limit, the Chern number of a translationally invariant system cannot change under unitary time evolutions that are smooth in momentum space. Yet a real-space counterpart of the Chern number, the Bott…

Quantum Gases · Physics 2018-05-01 Yang Ge , Marcos Rigol

We use the Dirac cone model to explore the high Chern number (C) phases that are realized in the magnetic-doped topological insulator (TI) multilayer structures by Zhao et al. [Nature 588, 419 (2020)]. The Chern number is calculated by…

Mesoscale and Nanoscale Physics · Physics 2022-08-19 Yi-Xiang Wang , Fuxiang Li

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

Topological invariants such as Chern classes are by now a standard way to classify topological phases. Introducing and varying parameters in such systems leads to phase diagrams, where the Chern classes may jump when crossing a critical…

Mathematical Physics · Physics 2025-05-21 Ralph M. Kaufmann , Mohamad Mousa , Birgit Wehefritz-Kaufmann

We present models of topological insulating Hamiltonians exhibiting intrinsic altermagnetic features, protected by combined three-fold or four-fold rotational symmetries with time-reversal. We demonstrate that the spin Chern number serves…

Mesoscale and Nanoscale Physics · Physics 2026-02-19 Rafael Gonzalez-Hernandez , Bernardo Uribe

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

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

Topological states of matter exhibit many novel properties due to the presence of robust topological invariants such as the Chern index. These global characteristics pertain to the system as a whole and are not locally defined. However,…

Strongly Correlated Electrons · Physics 2019-02-07 M. D. Caio , G. Möller , N. R. Cooper , M. J. Bhaseen

In commonly employed models for 2D topological insulators, bulk gapless states are well known to form at the band inversion points where the degeneracy of the states is protected by symmetries. It is thus sometimes quite tempting to…

Materials Science · Physics 2017-12-06 Wenjie Xi , Wei Ku

We construct a topological invariant that classifies density matrices of symmetry-protected topological orders in two-dimensional fermionic systems. As it is constructed out of the previously introduced Uhlmann phase, we refer to it as the…

Strongly Correlated Electrons · Physics 2014-08-26 O. Viyuela , A. Rivas , M. A. Martin-Delgado

We explore the critical properties of a topological transition in a two-dimensional, amorphous lattice with randomly distributed points. The model intrinsically breaks the time-reversal symmetry without an external magnetic field, akin to a…

Mesoscale and Nanoscale Physics · Physics 2025-10-24 Soumya Bera , Johannes Dieplinger , Naba P Nayak

Integer-valued topological indices, characterizing nonlocal properties of quantum states of matter, are known to directly predict robust physical properties of equilibrium systems. The Chern number, e.g., determines the quantized Hall…

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

In this paper we explore the effects of quasiperiodicity in paradigmatic models of Chern insulators. We identify a plethora of topological phase transitions and characterize them based on spectral and localization properties. Contrary to…

Disordered Systems and Neural Networks · Physics 2022-12-16 Tiago S. Gonçalves , Miguel Gonçalves , Pedro Ribeiro , Bruno Amorim