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The recent discovery of topological insulator (TI) offers new opportunities for the development of thermoelectrics, because many TIs (like Bi$_2$Te$_3$) are excellent thermoelectric (TE) materials. In this review, we will first describe the…

Materials Science · Physics 2016-10-26 Yong Xu

Topological insulators have been proposed to be best characterized as bulk magnetoelectric materials that show response functions quantized in terms of fundamental physical constants. Here we lower the chemical potential of…

Mesoscale and Nanoscale Physics · Physics 2016-12-07 Liang Wu , M. Salehi , N. Koirala , J. Moon , S. Oh , N. P. Armitage

Topological insulators are solid state systems of independent electrons for which the Fermi level lies in a mobility gap, but the Fermi projection is nevertheless topologically non-trivial, namely it cannot be deformed into that of a normal…

Mathematical Physics · Physics 2016-10-27 Hermann Schulz-Baldes

Higher-order topological insulators have been introduced in the precursory Benalcazar-Bernevig-Hughes quadrupole model, but no electronic compound has been proposed to be a quadrupole topological insulator (QTI) yet. In this work, we…

Materials Science · Physics 2022-09-08 Zhaopeng Guo , Junze Deng , Yue Xie , Zhijun Wang

Higher Order Topological Insulators (HOTI) are $d$-spatial dimensional systems featuring topologically protected gap-less states at their $(d-n)$-dimensional boundaries. With the help of \textit{ab-initio} calculations and tight binding…

Materials Science · Physics 2020-09-09 Santosh Kumar Radha , Walter R. L. Lambrecht

Chiral-antichiral pairs of non-Abelian Hall states, like the Pfaffian, Read-Rezayi and NASS states, can be used to model two-dimensional time-reversal invariant topological insulators. Their stability was shown to be associated to the…

Strongly Correlated Electrons · Physics 2015-06-22 Andrea Cappelli , Enrico Randellini

We analyze the topological $\mathbb{Z}_2$ invariant, which characterizes time reversal invariant topological insulators, in the framework of index theory and K-theory. The topological $\mathbb{Z}_2$ invariant counts the parity of…

Mathematical Physics · Physics 2018-10-30 Ralph M. Kaufmann , Dan Li , Birgit Wehefritz-Kaufmann

We propose magnetic second-order topological insulators (SOTIs). First, we study a three-dimensional model. It is pointed out that the previously proposed topological hinge insulator has actually surface states along the [001] direction in…

Mesoscale and Nanoscale Physics · Physics 2018-04-25 Motohiko Ezawa

We construct exactly soluble lattice models for fractionalized, time reversal invariant electronic insulators in 2 and 3 dimensions. The low energy physics of these models is exactly equivalent to a non-interacting topological insulator…

Strongly Correlated Electrons · Physics 2013-05-29 Michael Levin , F. J. Burnell , Maciej Koch-Janusz , Ady Stern

We review various features of interacting Abelian topological phases of matter in two spatial dimensions, placing particular emphasis on fractional Chern insulators (FCIs) and fractional topological insulators (FTIs). We highlight aspects…

Strongly Correlated Electrons · Physics 2015-11-17 Titus Neupert , Claudio Chamon , Thomas Iadecola , Luiz H. Santos , Christopher Mudry

Motivated by the topologically insulating (TI) circuit of capacitors and inductors proposed and tested in arXiv:1309.0878, we present a related circuit with less elements per site. The normal mode frequency matrix of our circuit is…

Mesoscale and Nanoscale Physics · Physics 2015-05-05 Victor V. Albert , Leonid I. Glazman , Liang Jiang

Second-order topological insulators (SOTI) exhibit protected gapless boundary states at their hinges or corners. In this paper, we propose a generic means to construct SOTIs in static and Floquet systems by coupling one-dimensional…

Mesoscale and Nanoscale Physics · Physics 2019-02-14 Raditya Weda Bomantara , Longwen Zhou , Jiaxin Pan , Jiangbin Gong

As an exotic quantum condensed matter, the topological insulator (TI) is a bulk-insulating material with a Dirac-type conducting surface state. Such dissipationless transport of topological surface states (TSSs) is protected by the…

Mesoscale and Nanoscale Physics · Physics 2017-10-24 Shuai Zhang , Zhaoguo Li , Fengqi Song

Three dimensional (3D) topological insulators (TIs) are an important class of materials with applications in electronics, spintronics and quantum computing. With the recent development of truly bulk insulating 3D TIs, it has become possible…

Topological insulators are a broad class of unconventional materials that are insulating in the interior but conduct along the edges. This edge transport is topologically protected and dissipationless. Until recently, all existing…

We propose new two-dimensional (2D) topological insulators (TIs) in functionalized germanenes (GeX, X=H, F, Cl, Br or I) using first-principles calculations. We find GeI is a 2D TI with a bulk gap of about 0.3 eV, while GeH, GeF, GeCl and…

Materials Science · Physics 2014-04-14 Chen Si , Junwei Liu , Yong Xu , Jian Wu , Bing-Lin Gu , Wenhui Duan

Recently, the theory of quantized dipole polarization has been extended to account for electric multipole moments, giving rise to the discovery of multipole topological insulators (TIs). Both two-dimensional (2D) quadrupole and…

Mesoscale and Nanoscale Physics · Physics 2020-09-16 Weixuan Zhang , Deyuan Zou , Wenjing He , Jiacheng Bao , Qingsong Pei , Houjun Sun , Xiangdong Zhang

This work concerns with the description of the topological phases of band insulators of class DIII by using the equivariant cohomology. The main result is the definition of a cohomology class for general systems of class DIII which…

Mathematical Physics · Physics 2022-09-28 Giuseppe De Nittis , Kiyonori Gomi

We theoretically predict two new classes of three-dimensional topological crystalline insulators (TCIs), which have an odd number of unpinned surface Dirac cones protected by crystal symmetries. The first class is protected by a single…

Mesoscale and Nanoscale Physics · Physics 2015-04-16 Chen Fang , Liang Fu

Symmetry-protected topological crystalline insulators (TCIs) have primarily been characterized by their gapless boundary states. However, in time-reversal- ($\mathcal{T}$-) invariant (helical) 3D TCI$\unicode{x2014}$termed higher-order TCIs…