scholarly journals General corner charge formula in two-dimensional Cn -symmetric higher-order topological insulators

2021 ◽  
Vol 103 (20) ◽  
Author(s):  
Ryo Takahashi ◽  
Tiantian Zhang ◽  
Shuichi Murakami
Keyword(s):  
Topological Insulators ◽  
Higher Order ◽  
Two Dimensional ◽  
Charge Formula

scholarly journals Observation of higher-order non-Hermitian skin effect

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xiujuan Zhang ◽  
Yuan Tian ◽  
Jian-Hua Jiang ◽  
Ming-Hui Lu ◽  
Yan-Feng Chen
Keyword(s):  
Topological Insulators ◽  
Skin Effect ◽  
Higher Dimensions ◽  
Higher Order ◽  
Dependent Manner ◽  
Two Dimensional ◽  
Band Theory ◽  
One Dimensional ◽  
Finite Systems ◽  
Spin Polarized

AbstractBeyond the scope of Hermitian physics, non-Hermiticity fundamentally changes the topological band theory, leading to interesting phenomena, e.g., non-Hermitian skin effect, as confirmed in one-dimensional systems. However, in higher dimensions, these effects remain elusive. Here, we demonstrate the spin-polarized, higher-order non-Hermitian skin effect in two-dimensional acoustic higher-order topological insulators. We find that non-Hermiticity drives wave localizations toward opposite edges upon different spin polarizations. More interestingly, for finite systems with both edges and corners, the higher-order non-Hermitian skin effect leads to wave localizations toward two opposite corners for all the bulk, edge and corner states in a spin-dependent manner. We further show that such a skin effect enables rich wave manipulation by configuring the non-Hermiticity. Our study reveals the intriguing interplay between higher-order topology and non-Hermiticity, which is further enriched by the pseudospin degree of freedom, unveiling a horizon in the study of non-Hermitian physics.

scholarly journals Discovery of higher-order topological insulators using the spin Hall conductivity as a topology signature

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Marcio Costa ◽  
Gabriel R. Schleder ◽  
Carlos Mera Acosta ◽  
Antonio C. M. Padilha ◽  
Frank Cerasoli ◽  
...  
Keyword(s):  
Density Functional ◽  
Topological Insulators ◽  
Tight Binding ◽  
Density Functional Theory Calculations ◽  
Higher Order ◽  
Hall Conductivity ◽  
Two Dimensional ◽  
Boundary States ◽  
Potential Applications ◽  
Spin Hall Conductivity

AbstractThe discovery and realization of topological insulators, a phase of matter which hosts metallic boundary states when the d-dimension insulating bulk is confined to (d − 1)-dimensions, led to several potential applications. Recently, it was shown that protected topological states can manifest in (d − 2)-dimensions, such as hinge and corner states for three- and two-dimensional systems, respectively. These nontrivial materials are named higher-order topological insulators (HOTIs). Here we show a connection between spin Hall effect and HOTIs using a combination of ab initio calculations and tight-binding modeling. The model demonstrates how a non-zero bulk midgap spin Hall conductivity (SHC) emerges within the HOTI phase. Following this, we performed high-throughput density functional theory calculations to find unknown HOTIs, using the SHC as a criterion. We calculated the SHC of 693 insulators resulting in seven stable two-dimensional HOTIs. Our work guides novel experimental and theoretical advances towards higher-order topological insulator realization and applications.

scholarly journals Higher-order topological insulators in two-dimensional Dirac materials

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Yang Xue ◽  
Hao Huan ◽  
Bao Zhao ◽  
Youhua Luo ◽  
Zhenyu Zhang ◽  
...  
Keyword(s):  
Topological Insulators ◽  
Higher Order ◽  
Two Dimensional ◽  
Dirac Materials

Two-Dimensional Local Deep-Level Transient Spectroscopy Imaging Using Super-Higher-Order Scanning Nonlinear Dielectric Microscopy

2016 ◽  
Author(s):  
N. Chinone ◽  
Y. Cho ◽  
R. Kosugi ◽  
Y. Tanaka ◽  
S. Harada ◽  
...  
Keyword(s):  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Higher Order ◽  
Trap Density ◽  
New Technique ◽  
Two Dimensional ◽  
Nonlinear Dielectric ◽  
Annealing Conditions ◽  
Transient Spectroscopy ◽  
A New Technique

Abstract A new technique for local deep level transient spectroscopy (DLTS) imaging using super-higher-order scanning nonlinear dielectric microscopy is proposed. Using this technique. SiCVSiC structure samples with different post oxidation annealing conditions were measured. We observed that the local DLTS signal decreases with post oxidation annealing (POA), which agrees with the well-known phenomena that POA reduces trap density. Furthermore, obtained local DLTS images had dark and bright areas, which is considered to show the trap distribution at/near SiCVSiC interface.

Two-dimensional topological insulators exfoliated from Na3Bi-like Dirac semimetals

2021 ◽  
Author(s):  
Xiaoqiu Guo ◽  
Ruixin Yu ◽  
Jingwen Jiang ◽  
Zhuang Ma ◽  
Xiuwen Zhang
Keyword(s):  
Physical Properties ◽  
Epitaxial Growth ◽  
Topological Insulators ◽  
2D Materials ◽  
Van Der Waals ◽  
Two Dimensional ◽  
Dirac Semimetals

Topological insulation is widely predicted in two-dimensional (2D) materials realized by epitaxial growth or van der Waals (vdW) exfoliation. Such 2D topological insulators (TI’s) host many interesting physical properties such...

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