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A P-N junction engineered within a Dirac cone system acts as a gate tunable angular filter based on Klein tunneling. For a 3D topological insulator with substantial bandgap, such a filter can produce a charge-to-spin conversion due to the…

Mesoscale and Nanoscale Physics · Physics 2021-11-23 Hamed Vakili , Yunkun Xie , Samiran Ganguly , Avik W. Ghosh

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…

Topological insulators in the Bi$_2$Se$_3$ family manifest helical Dirac surface states that span the topologically ordered bulk band gap. Recent scanning tunneling microscopy measurements have discovered additional states in the bulk band…

Materials Science · Physics 2018-08-01 Yishuai Xu , Guodong Jiang , Janet Chiu , Lin Miao , Erica Kotta , Yutan Zhang , Rudro R. Biswas , L. Andrew Wray

The recent discovered antiferromagnetic topological insulators in Mn-Bi-Te family with intrinsic magnetic ordering have rapidly drawn broad interest since its cleaved surface state is believed to be gapped, hosting the unprecedented axion…

By combining $n$-type $\mathrm{Bi_2Te_3}$ and $p$-type $\mathrm{Sb_2Te_3}$ topological insulators, vertically stacked $p$-$n$ junctions can be formed, allowing to position the Fermi level into the bulk band gap and also tune between $n$-…

Mesoscale and Nanoscale Physics · Physics 2017-09-27 D. Backes , D. Huang , R. Mansell , M. Lanius , J. Kampmeier , D. A. Ritchie , G. Mussler , G. Gumbs , D. Grützmacher , V. Narayan

We review recent progress in the electronic structure study of intrinsic magnetic topological insulators (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$ ($n=0,1,2,3$) family. Specifically, we focus on the ubiquitously (nearly) gapless behavior of the…

Topological insulators are new states of matter with a bulk gap and robust gapless surface states protected by time-reversal symmetry. When time-reversal symmetry is broken, the surface states are gapped, which induces a topological…

Materials Science · Physics 2015-03-20 Weidong Luo , Xiao-Liang Qi

We investigate the surface state of Bi$_2$Te$_3$ using angle resolved photoemission spectroscopy (ARPES) and transport measurements. By scanning over the entire Brillouin zone (BZ), we demonstrate that the surface state consists of a single…

Three dimensional topological insulator crystals consist of an insulating bulk enclosed by metallic surfaces, and detailed theoretical predictions about the surface state band topology and spin texture are available. While several…

Existence of a protected surface state described by a massless Dirac equation is a defining property of the topological insulator. Though this statement can be explicitly verified on an idealized flat surface, it remains to be addressed to…

Mesoscale and Nanoscale Physics · Physics 2013-06-18 Yositake Takane , Ken-Ichiro Imura

Topological insulators are novel macroscopic quantum-mechanical phase of matter, which hold promise for realizing some of the most exotic particles in physics as well as application towards spintronics and quantum computation. In all the…

We study electronic structures at an interface between a topological insulator and a ferromagnetic insulator by using three-dimensional two-band model. In usual ferromagnetic insulators, the exchange potential is much larger than the bulk…

Mesoscale and Nanoscale Physics · Physics 2012-11-21 Tetsuro Habe , Yasuhiro Asano

The unoccupied states in topological insulators Bi_2Se_3, PbSb_2Te_4, and Pb_2Bi_2Te_2S_3 are studied by the density functional theory methods. It is shown that a surface state with linear dispersion emerges in the inverted conduction band…

Materials Science · Physics 2015-06-15 S. V. Eremeev , I. V. Silkin , T. V. Menshchikova , A. P. Protogenov , E. V. Chulkov

Topological insulators are a new class of insulators in which a bulk gap for electronic excitations is generated by strong spin orbit coupling. These novel materials are distinguished from ordinary insulators by the presence of gapless…

We investigate the properties of a single substitutional Mn impurity and its associated acceptor state on the (111) surface of Bi$_2$Se$_3$ topological insulator. Combining ab initio calculations with microscopic tight-binding modeling, we…

Materials Science · Physics 2014-12-01 M. R. Mahani , A. Pertsova , M. Fhokru Islam , C. M. Canali

Single-Dirac-cone topological insulators (TI) are the first experimentally discovered class of three dimensional topologically ordered electronic systems, and feature robust, massless spin-helical conducting surface states that appear at…

Topological insulators embody a newly discovered state of matter characterized by conducting spin-momentum locked surface states that span the bulk band gap. So far, most of the study on topological insulator surfaces has been limited to…

Mesoscale and Nanoscale Physics · Physics 2012-06-04 L. A. Wray , Y. Xia , S. -Y. Xu , Y. S. Hor , R. J. Cava , A. Bansil , H. Lin , M. Z. Hasan

The surface of a topological insulator is a closed two dimensional manifold. The surface states are described by the Dirac Hamiltonian in curved two dimensional spaces. For a slab-like sample with a magnetic field perpendicular to its top…

Mesoscale and Nanoscale Physics · Physics 2013-05-29 Dung-Hai Lee

Topological insulators are electronic materials that have a bulk band gap like an ordinary insulator, but have protected conducting states on their edge or surface. The 2D topological insulator is a quantum spin Hall insulator, which is a…

Mesoscale and Nanoscale Physics · Physics 2015-03-13 M. Z. Hasan , C. L. Kane

The surface of a topological crystalline insulator (TCI) carries an even number of Dirac cones protected by crystalline symmetry. We epitaxially grew high quality Pb$_{1-x}$Sn$_x$Te(111) films and investigated the TCI phase by in-situ…