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Bi$_{2}$Se$_{3}$ is a topological insulator whose unique properties result from topological surface states (TSS) in the band gap. Low energy ion scattering can determine the properties of the outermost few atomic layers of a solid. The…

Mesoscale and Nanoscale Physics · Physics 2018-11-20 Weimin Zhou , Haoshan Zhu , Jory A. Yarmoff

Topological insulators (TI) are materials having an energy band gap in the bulk and conducting helical electronic states on the surface. The helical states are protected by time reversal symmetry thus are expected to be robust against…

Mesoscale and Nanoscale Physics · Physics 2012-11-26 Xue-Feng Wang , Yibin Hu , Hong Guo

The binary chalcogenides Bi2Te3 and Bi2Se3 are the most widely studied topological insulators. Although the quantum anomalous Hall effect has recently been observed in magnetically doped Sb2Te3 this compound has been studied to a much…

Mesoscale and Nanoscale Physics · Physics 2016-02-17 P. Sessi , O. Storz , T. Bathon , S. Wilfert , K. A. Kokh , O. E. Tereshchenko , G. Bihlmayer , M. Bode

We study theoretically the distributions of charge and spin polarization of a topological insulator ribbon, with a realistic rectangular cross section. Due to constriction in two lateral directions, the surface states discretize into a…

Materials Science · Physics 2011-12-13 Lei Hao , Peter Thalmeier , T. K. Lee

We show that the surface states in topological insulators can be understood based on a well-known Shockley model, a one-dimensional tight-binding model with two atoms per elementary cell, connected via alternating tunneling amplitudes. We…

Strongly Correlated Electrons · Physics 2012-08-30 Sergey S. Pershoguba , Victor M. Yakovenko

Aiming at the future spintronics device applications of the spin-polarized surface states in three-dimensional topological insulator, a highly insulating bulk state and a tunable Dirac cone surface state are required. Here we employ a slab…

Materials Science · Physics 2020-01-01 Takao Kosaka , Kunihiko Yamauchi , Tamio Oguchi

The topological invariant of a topological insulator (or superconductor) is given by the number of symmetry-protected edge states present at the Fermi level. Despite this fact, established expressions for the topological invariant require…

Mesoscale and Nanoscale Physics · Physics 2013-01-11 I. C. Fulga , F. Hassler , A. R. Akhmerov

Two-dimensional topological insulators are characterized by gapped bulk states and gapless helical edge states, i.e. time-reversal symmetric edge states accommodating a pair of counter-propagating electrons. An external magnetic field…

Mesoscale and Nanoscale Physics · Physics 2012-04-02 G. Tkachov , E. M. Hankiewicz

We study strong f-electron localization effect on surface state of a generic topological Kondo insulator (TKI) system by performing a mean-field theoretic (MFT) calculation within the frame-work of periodic Anderson model (PAM) using…

Strongly Correlated Electrons · Physics 2021-11-29 U. P. Tyagi , Kakoli Bera , Partha Goswami

We study the surface of a three-dimensional spin chiral $\mathrm{Z}_2$ topological insulator (class CII), demonstrating the possibility of its localization. This arises through an interplay of interaction and statistically-symmetric…

Strongly Correlated Electrons · Physics 2019-04-17 Yang-Zhi Chou , Rahul M. Nandkishore , Leo Radzihovsky

Topological insulators are a recently discovered class of materials with fascinating properties: While the inside of the solid is insulating, fundamental symmetry considerations require the surfaces to be metallic. The metallic surface…

The quantum spin Hall (QSH) effect is the property of a new state of matter which preserves time-reversal, has an energy gap in the bulk, but has topologically robust gapless states at the edge. Recently, it has been shown that HgTe quantum…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 Xi Dai , Taylor L. Hughes , Xiao-Liang Qi , Zhong Fang , Shou-Cheng Zhang

Topological insulators in three dimensions are nonmagnetic insulators that possess metallic surface states as a consequence of the nontrivial topology of electronic wavefunctions in the bulk of the material. They are the first known…

Strongly Correlated Electrons · Physics 2012-01-26 M. Zahid Hasan , Joel E. Moore

To gain further insight into the properties of interacting topological insulators, we study a 1 dimensional model of topological Kondo insulators which can be regarded as the strongly interacting limit of the Tamm-Shockley model. Treating…

Strongly Correlated Electrons · Physics 2014-10-01 Victor Alexandrov , Piers Coleman

Gapless surface states that are protected by time reversal symmetry and charge conservation are among the manifestations of 3D topological insulators. In this work we study how electron-electron interaction may lead to spontaneous breaking…

Strongly Correlated Electrons · Physics 2012-06-07 Yuval Baum , Ady Stern

We report on the observation of cyclotron resonance induced photocurrents, excited by continuous wave terahertz radiation, in a 3D topological insulator (TI) based on an 80 nm strained HgTe film. The analysis of the photocurrent formation…

Electronic transport experiments involving the topologically protected states found at the surface of Bi2Se3 and other topological insulators require fine control over carrier density, which is challenging with existing bulk-doped material.…

Mesoscale and Nanoscale Physics · Physics 2010-12-14 Hadar Steinberg , Dillon R. Gardner , Young S. Lee , Pablo Jarillo-Herrero

The discovery of three-dimensional (3D) topological insulators opens a gateway to generate unusual phases and particles made of the helical surface electrons, proposing new applications using unusual spin nature. Demonstration of the…

Mesoscale and Nanoscale Physics · Physics 2014-04-04 Seung Sae Hong , Yi Zhang , Judy J. Cha , Xiao-Liang Qi , Yi Cui

We have performed broad-band zero-field and magneto-infrared spectroscopy of the three dimensional topological insulator Bi$_{0.91}$Sb$_{0.09}$. The zero-field results allow us to measure the value of the direct band gap between the…

Mesoscale and Nanoscale Physics · Physics 2015-06-04 A. A. Schafgans , A. A. Taskin , Yoichi Ando , Xiao-Liang Qi , B. C. Chapler , K. W. Post , D. N. Basov

Despite the broadband response, limited optical absorption at a particular wavelength hinders the development of optoelectronics based on Dirac fermions. Heterostructures of graphene and various semiconductors have been explored for this…