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We have studied the energy dispersion of the Dirac bands of the topological insulator Bi2Se3 at large parallel momenta using a setup for laser-based time-resolved momentum microscopy with 6 eV probe-photons. Using this setup, we can probe…

Topological insulators represent novel phases of quantum matter with an insulating bulk gap and gapless edges or surface states. The two-dimensional topological insulator phase was predicted in HgTe quantum wells and confirmed by transport…

Mesoscale and Nanoscale Physics · Physics 2015-05-14 Hailin Peng , Keji Lai , Desheng Kong , Stefan Meister , Yulin Chen , Xiao-Liang Qi , Shou-Cheng Zhang , Zhi-Xun Shen , Yi Cui

Three-dimensional topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering. The static electronic properties of these surface states have been comprehensively…

Mesoscale and Nanoscale Physics · Physics 2011-12-06 J. W. McIver , D. Hsieh , H. Steinberg , P. Jarillo-Herrero , N. Gedik

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

We characterize the occupied and unoccupied electronic structure of the topological insulator Bi$_2$Se$_3$ by one-photon and two-photon angle-resolved photoemission spectroscopy and slab band structure calculations. We reveal a second,…

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…

The opacity of graphene is known to be approximately given by the fine-structure constant $\alpha$ times $\pi$. We point out the fact that the opacity is roughly independent of the frequency and polarization of the light can be attributed…

Mesoscale and Nanoscale Physics · Physics 2023-10-10 Matheus S. M. de Sousa , Wei Chen

Topological insulators generally have dielectric bulk and conductive surface states. Consequently, some of these materials have been shown to support polaritonic modes at visible and THz frequencies. At the same time, the optical properties…

Materials Science · Physics 2024-02-27 Sergey G. Menabde , Jacob T. Heiden , Vladimir A. Zenin , N. Asger Mortensen , Min Seok Jang

Several small-bandgap semiconductors are now known to have protected metallic surface states as a consequence of the topology of the bulk electron wavefunctions. The known "topological insulators" with this behavior include the important…

Mesoscale and Nanoscale Physics · Physics 2013-01-01 Pouyan Ghaemi , Roger Mong , Joel E. Moore

Three-dimensional (3D) topological insulators (TI) are novel quantum materials with insulating bulk and topologically protected metallic surfaces with Dirac-like band structure. The spin-helical Dirac surface states are expected to host…

Recent theories and experiments have suggested that strong spin-orbit coupling effects in certain band insulators can give rise to a new phase of quantum matter, the so-called topological insulator, which can show macroscopic entanglement…

Mesoscale and Nanoscale Physics · Physics 2009-08-26 Y. Xia , D. Qian , D. Hsieh , L. Wray , A. Pal , H. Lin , A. Bansil , D. Grauer , Y. S. Hor , R. J. Cava , M. Z. Hasan

Bi2Se3, Bi2Te3 and Sb2Te3 compounds are recently predicted to be 3-dimentional (3D) strong topological insulators. In this paper, based on ab-initio calculations, we study in detail the topological nature and the surface states of this…

Materials Science · Physics 2010-08-25 Wei Zhang , Rui Yu , Hai-Jun Zhang , Xi Dai , Zhong Fang

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…

We report thermoelectric (TE) properties of topological surface Dirac states (TSDS) in three-dimensional topological insulators (3D-TIs) purely isolated from the bulk by employing single crystal Bi$_{2-x}$Sb$_x$Te$_{3-y}$Se$_y$ films…

By combining transport and photo emission measurements on (Bi1-xInx)2Se3 thin films, we report that this system transforms from a topologically non-trivial metal into a topologically trivial band insulator through three quantum phase…

Mesoscale and Nanoscale Physics · Physics 2012-11-02 Matthew Brahlek , Namrata Bansal , Nikesh Koirala , Su-Yang Xu , Madhab Neupane , Chang Liu , M. Zahid Hasan , Seongshik Oh

We calculate the local density of states of two prototypical topological insulators (Bi$_2$Se$_3$ and Bi$_2$Te$_2$Se) as a function of distance from the surface within density functional theory. We find that, in the absence of disorder or…

Mesoscale and Nanoscale Physics · Physics 2015-10-08 Benjamin M. Fregoso , Sinisa Coh

The existence of gapless Dirac surface band of a three dimensional (3D) topological insulator (TI) is guaranteed by the non-trivial topological character of the bulk band, yet the surface band dispersion is mainly determined by the…

Mesoscale and Nanoscale Physics · Physics 2015-09-24 Cui-Zu Chang , Peizhe Tang , Xiao Feng , Kang Li , Xu-Cun Ma , Wenhui Duan , Ke He , Qi-Kun Xue

The two-dimensional (2D) surface state of the three-dimensional strong topological insulator (STI) is fundamentally distinct from other 2D electron systems in that the Fermi arc encircles an odd number of Dirac points. The TI surface is in…

Mesoscale and Nanoscale Physics · Physics 2013-06-28 Dohun Kim , Paul Syers , Nicholas P. Butch , Johnpierre Paglione , Michael S. Fuhrer

Three-dimensional topological insulators (TIs) attract much attention due to its topologically protected Dirac surface states. Doping into TIs or their proximity with normal superconductors can promote the realization of topological…

Superconductivity · Physics 2024-12-16 Tian Le , Qikai Ye , Chufan Chen , Lichang Yin , Dongting Zhang , Xiaozhi Wang , Xin Lu

We report the observation of a novel nonlinear optical response from the prototypical three-dimensional topological insulator Bi$_2$Se$_3$ through the process of high-order harmonic generation. We find that the generation efficiency…