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We expand the concept of two-dimensional topological insulators to encompass a novel category known as topological dipole insulators (TDIs), characterized by conserved dipole moments along the $x$-direction in addition to charge…

Mesoscale and Nanoscale Physics · Physics 2024-11-20 Ho Tat Lam , Jung Hoon Han , Yizhi You

We study the bulk and boundary properties of fragile topological insulators (TIs) protected by inversion symmetry, mostly focusing on the class A of the Altland-Zirnbauer classification. First, we propose an efficient method for diagnosing…

Mesoscale and Nanoscale Physics · Physics 2019-11-21 Yoonseok Hwang , Junyeong Ahn , Bohm-Jung Yang

We explore the 32 crystallographic point groups and identify topological phases of matter with robust surface modes. For n =3,4 and 6 of the C_{nv} groups, we find the first-known 3D topological insulators without spin-orbit coupling, and…

Strongly Correlated Electrons · Physics 2014-09-17 A. Alexandradinata , Chen Fang , Matthew J. Gilbert , B. Andrei Bernevig

Topological semimetals with symmetry-protected band crossings have emerged as a rich landscape to explore intriguing electronic phenomena. Nonsymmorphic symmetries in particular have been shown to play an important role in protecting the…

Band insulators appear in a crystalline system only when the filling -- the number of electrons per unit cell and spin projection -- is an integer. At fractional filling, an insulating phase that preserves all symmetries is a Mott…

Strongly Correlated Electrons · Physics 2013-05-07 S. A. Parameswaran , Ari M. Turner , Daniel P. Arovas , Ashvin Vishwanath

Quasicrystals allow for symmetries that are impossible in crystalline materials, such as eight-fold rotational symmetry, enabling the existence of novel higher-order topological insulators in two dimensions without crystalline counterparts.…

Mesoscale and Nanoscale Physics · Physics 2024-05-13 Yu-Feng Mao , Yu-Liang Tao , Jiong-Hao Wang , Qi-Bo Zeng , Yong Xu

A quadrupole topological insulator, being one higher-order topological insulator with nontrivial quadrupole quantization, has been intensely investigated very recently. However, the tight-binding model proposed for such emergent topological…

Mesoscale and Nanoscale Physics · Physics 2020-12-09 Yajuan Qi , Chunyin Qiu , Meng Xiao , Hailong He , Manzhu Ke , Zhengyou Liu

Recent theoretical advances have proposed a new class of topological crystalline insulator (TCI) phases protected by rotational symmetries. Distinct from topological insulators (TIs), rotational symmetry-protected TCIs are expected to show…

Strongly correlated analogues of topological insulators have been explored in systems with purely on-site symmetries, such as time-reversal or charge conservation. Here, we use recently developed tensor network tools to study a quantum…

Strongly Correlated Electrons · Physics 2015-11-11 Brayden Ware , Itamar Kimchi , S. A. Parameswaran , Bela Bauer

In this work, we identify a new class of Z2 topological insulator protected by non-symmorphic crystalline symmetry, dubbed a "topological non-symmorphic crystalline insulator". We construct a concrete tight-binding model with the…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Chao-Xing Liu , Rui-Xing Zhang

Crystalline topological insulators owe their topological character to the protection that certain boundary states acquire because of certain point-group symmetries. We first show that a Hermitian operator obeying supersymmetric quantum…

Strongly Correlated Electrons · Physics 2014-11-07 Po-Yao Chang , Christopher Mudry , Shinsei Ryu

We show that there exist two dimensional (2D) time reversal invariant fractionalized insulators with the property that both their boundary with the vacuum and their boundary with a topological insulator can be fully gapped without breaking…

Strongly Correlated Electrons · Physics 2014-04-21 Chenjie Wang , Michael Levin

The modern theory of electric polarization has recently been extended to higher multipole moments, such as quadrupole and octupole moments. The higher electric multipole insulators are essentially topological crystalline phases protected by…

Mesoscale and Nanoscale Physics · Physics 2020-05-27 Chang-An Li , Shu-Shan Wu

Based on first-principles calculations and symmetry-based indicator analysis, we find a class of topological crystalline insulators (TCIs) with $C_2$ rotation anomaly in a family of Zintl compounds, including…

Materials Science · Physics 2019-08-14 Tan Zhang , Changming Yue , Tiantian Zhang , Simin Nie , Zhijun Wang , Chen Fang , Hongming Weng , Zhong Fang

Our understanding of topological insulators is based on an underlying crystalline lattice where the local electronic degrees of freedom at different sites hybridize with each other in ways that produce nontrivial band topology, and the…

Mesoscale and Nanoscale Physics · Physics 2017-10-03 Adhip Agarwala , Vijay B. Shenoy

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

Time reversal (T) invariant topological insulator is widely recognized as one of the fundamental discoveries in condensed matter physics, for which the most fascinating hallmark is perhaps a spin based topological protection, the total…

Mesoscale and Nanoscale Physics · Physics 2017-01-17 Xue-Feng Zhu , Yu-Gui Peng , Xiang-Yuan Yu , Han Jia , Ming Bao , Ya-Xi Shen , De-Gang Zhao

The modern theory of electric polarization in crystals associates the dipole moment of an insulator with a Berry phase of its electronic ground state [1, 2]. This concept constituted a breakthrough that not only solved the long-standing…

Mesoscale and Nanoscale Physics · Physics 2018-04-18 Christopher W. Peterson , Wladimir A. Benalcazar , Taylor L. Hughes , Gaurav Bahl

Second-order topological insulators can be characterized by their bulk polarization, which is believed to be intrinsically connected to the center of the Wannier function. In this study, we demonstrate the existence of second-order…

Mesoscale and Nanoscale Physics · Physics 2024-05-06 Zhenzhen Liu , Xiaoxi Zhou , Guochao Wei , Lei Gao , Bo hou , Jun-Jun Xiao

In this Letter, we study a previously unexplored class of topological states protected by hidden chiral symmetries that are local, that is, that protect against any off-diagonal disorder. We derive their related topological invariant for…

Mesoscale and Nanoscale Physics · Physics 2025-04-08 Juan Zurita , Charles E. Creffield , Gloria Platero