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We consider the extent to which symmetry eigenvalues reveal the topological character of bands. Specifically, we compare distinct atomic limit phases (band representations) that share the same irreducible representations (irreps) at all…

Mesoscale and Nanoscale Physics · Physics 2022-03-23 Jennifer Cano , L. Elcoro , M. I. Aroyo , B. Andrei Bernevig , Barry Bradlyn

Interfaces between exfoliated topological insulator Bi2Se3 and several transition metals deposited by sputtering were studied by XPS, SIMS, UPS and contact I-V measurements. Chemically clean interfaces can be achieved when coating Bi2Se3…

Mesoscale and Nanoscale Physics · Physics 2015-11-12 Weiguang Ye , A. B. Pakhomov , Shuigang Xu , Huanhuan Lu , Zefei Wu , Yu Han , Tianyi Han , Yingying Wu , Gen Long , Jiangxiazi Lin , Gu Xu , Yuan Cai , Lu-Tao Weng , Ning Wang

While the symmetry-based diagnosis of topological insulators and semimetals has enabled large-scale discovery of topological materials candidates, the extension of these approaches to the diagnosis of topological superconductors remains a…

Superconductivity · Physics 2021-05-12 Seishiro Ono , Hoi Chun Po , Ken Shiozaki

We discuss the applicability of elementary band representations (EBRs) to diagnose spatial- and time-reversal-symmetry protected topological phases in interacting insulators in terms of their single-particle Green's functions. We do so by…

Strongly Correlated Electrons · Physics 2021-08-31 Dominik Lessnich , Stephen M. Winter , Mikel Iraola , Maia G. Vergniory , Roser Valentí

Mathematically, topological invariants arise from the parallel transport of eigenstates on the energy bands, which, in physics, correspond to the adiabatic dynamical evolution of transient states. It determines the presence of boundary…

Mesoscale and Nanoscale Physics · Physics 2025-04-04 Zhao-Xian Chen , Yuan-hong Zhang , Xiao-Chen Sun , Ruo-Yang Zhang , Jiang-Shan Tang , Xin Yang , Xue-Feng Zhu , Yan-Qing Lu

The Euler class characterizes the topology of two real bands isolated from other bands in two-dimensions. Despite various intriguing topological properties predicted up to now, the candidate real materials hosting electronic Euler bands are…

Mesoscale and Nanoscale Physics · Physics 2024-04-26 Seung Hun Lee , Yuting Qian , Bohm-Jung Yang

We introduce a class of singular connections as an alternative to the Berry connection for any family of quantum states defined over a parameter space. We find a natural application of the singular connection in the context of transition…

Mesoscale and Nanoscale Physics · Physics 2022-12-21 Bruno Mera , Tomoki Ozawa

We demonstrate the existence of topological insulators in one dimension protected by mirror and time-reversal symmetries. They are characterized by a nontrivial $\mathbb{Z}_2$ topological invariant defined in terms of the "partial"…

Mesoscale and Nanoscale Physics · Physics 2016-10-27 Alexander Lau , Jeroen van den Brink , Carmine Ortix

It is desirable to realize topological phases in artificial structures by engineering electronic band structures. In this paper, we investigate $(PbTe)_m(SnTe)_{2n-m}$ superlattices along [001] direction and find a robust weak topological…

Materials Science · Physics 2014-02-25 Gang Yang , Junwei Liu , Liang Fu , Wenhui Duan , Chaoxing Liu

Topological insulators are insulating in the bulk but feature conducting states on their surfaces. Standard methods for probing their topological properties largely involve probing the surface, even though topological invariants are defined…

We discuss the relation between bulk topological invariants and the spectrum of surface states in three dimensional non-interacting topological insulators. By studying particular models, and considering general boundary conditions for the…

Mesoscale and Nanoscale Physics · Physics 2015-05-27 L. Isaev , Y. H. Moon , G. Ortiz

Recent formal classifications of crystalline topological insulators predict that the combination of time-reversal and rotational symmetry gives rise to topological invariants beyond the ones known for other lattice symmetries. Although the…

Strongly Correlated Electrons · Physics 2021-12-01 Jans Henke , Mert Kurttutan , Jorrit Kruthoff , Jasper van Wezel

The topological invariants of band insulators are usually assumed to depend only on the connectivity between orbitals and not on their intra-cell position (orbital embedding), which is a separate piece of information in the tight-binding…

Mesoscale and Nanoscale Physics · Physics 2021-12-24 J. -N. Fuchs , F. Piéchon

For a many-body system of arbitrary dimension, we consider fermionic ground states of non-interacting Hamiltonians invariant under a $C_2$ cyclic group. The absolute difference $\Delta$ between the number of occupied symmetric and…

Strongly Correlated Electrons · Physics 2023-03-06 K. Monkman , J. Sirker

In this letter, we investigate topological phases of full-gapped odd-parity superconductors, which are distinguished by the bulk topological invariants and the topologically protected gapless boundary states. Using the particle-hole…

Superconductivity · Physics 2010-10-20 Masatoshi Sato

This paper reviews several analytic tools for the field of topological insulators, developed with the aid of non-commutative calculus and geometry. The set of tools includes bulk topological invariants defined directly in the thermodynamic…

Statistical Mechanics · Physics 2010-06-22 Emil Prodan

As for a generic parameter dependent hamiltonian with the time reversal (TR) invariance, a non Abelian Berry connection with the Kramers (KR) degeneracy are introduced by using a quaternionic Berry connection. This quaternionic structure…

Mesoscale and Nanoscale Physics · Physics 2010-08-27 Y. Hatsugai

In this work, we undertake a perturbative analysis of the topological non-Abelian Chern-Simons-Wong model with the aim to explicitly construct the second-order on-shell action. The resulting action is a topological quantity depending solely…

High Energy Physics - Theory · Physics 2024-06-03 M. Anda , E. Fuenmayor , L. Leal , E. Contreras

Using spin-resolved and angle-resolved photoemission spectroscopy and first-principles calculations, we have identified bulk band inversion and spin polarized surface state evolved from a weak topological insulator (TI) phase in van der…

We study disordered topological insulators with time reversal symmetry. Relying on the noncommutative index theorem which relates the Chern number to the projection onto the Fermi sea and the magnetic flux operator, we give a precise…

Mathematical Physics · Physics 2016-03-03 Hosho Katsura , Tohru Koma