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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

A pair of Dirac points (analogous to a vortex-antivortex pair) associated with opposite topological numbers (with $\pm\pi$ Berry phases) can be merged together through parameter tuning and annihilated to gap the Dirac spectrum, offering a…

Mesoscale and Nanoscale Physics · Physics 2019-11-20 Yang Xu , Guodong Jiang , Ireneusz Miotkowski , Rudro R. Biswas , Yong P. Chen

Bi2Te3 is a member of a new class of materials known as topological insulators which are supposed to be insulating in the bulk and conducting on the surface. However experimental verification of the surface states has been difficult in…

Strongly Correlated Electrons · Physics 2015-06-22 Sourabh Barua , K. P. Rajeev , Anjan K. Gupta

We discuss the excitation spectra around the Dirac node on a surface of a three-dimensional topological insulator. By using the diagrammatic expansion, we show that the coupling of an electron with the gauge field in the presence of…

Mesoscale and Nanoscale Physics · Physics 2013-05-09 Tetsuro Habe , Yasuhiro Asano

In order to stabilize Majorana excitations within vortices of proximity induced topological superconductors, it is mandatory that the Dirac point matches the Fermi level rather exactly, such that the conventionally confined states within…

We identify the multi-layered compound GeBi4Te7 to be a topological insulator with a freestanding Dirac point, slightly above the valence band maximum, using angle-resolved photoemission spectroscopy (ARPES) measurements. The spin…

Topological crystalline insulators (TCI) are a new class of materials which have metallic surface states on select surfaces due to point group crystalline symmetries. In this letter, we consider a model for a three-dimensional (3D)…

Mesoscale and Nanoscale Physics · Physics 2017-04-12 Srinidhi T. Ramamurthy , Yuxuan Wang , Taylor L. Hughes

An interface electron state at the junction between a three-dimensional topological insulator (TI) film of Bi2Se3 and a ferrimagnetic insulator film of Y3Fe5O12 (YIG) was investigated by measurements of angle-resolved photoelectron…

Bismuth has recently attracted interest in connection with Na-ion battery anodes due to its high volumetric capacity. It reacts with Na to form Na$_3$Bi which is a prototypical Dirac semimetal with a nontrivial electronic structure.…

A single Dirac cone on the surface is the hallmark of three-dimensional (3D) topological insulators, where the double degeneracy at the Dirac point is protected by time-reversal symmetry and the spin-splitting away from the point is…

Mesoscale and Nanoscale Physics · Physics 2016-01-05 Ling Lu , Chen Fang , Liang Fu , Steven G. Johnson , John D. Joannopoulos , Marin Soljačić

The spin-momentum locking at the Dirac surface state of a topological insulator (TI) offers a distinct possibility of a highly efficient charge-to-spin current (C-S) conversion compared with spin Hall effects in conventional paramagnetic…

Materials Science · Physics 2016-11-22 K. Kondou , R. Yoshimi , A. Tsukazaki , Y. Fukuma , J. Matsuno , K. S. Takahashi , M. Kawasaki , Y. Tokura , Y. Otani

In this paper, we investigate the topological properties of ZrRuP and ScPd$_{3}$ using the first-principles calculations. We calculate the electronic structure, surface states, and Z$_{2}$ topological invariant. The band structure of ZrRuP…

Materials Science · Physics 2018-01-10 Armindo S. Cuamba , Hong-Yan Lu , Lei Hao , C. S. Ting

We have investigated the surface and bulk electronic structures of the superconducting type-II Dirac semimetal 1T-PdSeTe. The superconducting transition temperature $T_C = 3.2$ K was almost twice as high as $T_C = 1.6$ K in 1T-PdTe$_2$.…

A topological insulator is a new state of matter, possessing gapless spin-locking surface states across the bulk band gap which has created new opportunities from novel electronics to energy conversion. However, the large concentration of…

Mesoscale and Nanoscale Physics · Physics 2013-03-08 Seung Sae Hong , Judy J. Cha , Desheng Kong , Yi Cui

It is well established that topological insulators sustain Dirac fermion surface states as a consequence of band inversion in the bulk. These states have a helical spin polarization and a linear dispersion with large Fermi velocity. In this…

Using time-, spin- and angle-resolved photoemission, we investigate the ultrafast spin dynamics of hot electrons on the surface of the topological insulator Bi$_2$Te$_3$ following optical excitation by fs-infrared pulses. We observe two…

Mesoscale and Nanoscale Physics · Physics 2017-05-22 J. Sánchez-Barriga , M. Battiato , M. Krivenkov , E. Golias , A. Varykhalov , A. Romualdi , L. V. Yashina , J. Minár , O. Kornilov , H. Ebert , K. Held , J. Braun

The exploration of topological Dirac surface states is significant in the realms of condensed matter physics and future technological innovations. Among the materials garnering attention is Sb$_{2}$Te$_{3}$, a compound that theoretically…

High resolution angle-resolved photoemission measurements have been carried out on transition metal dichalcogenide PdTe2 that is a superconductor with a Tc at 1.7 K. Combined with theoretical calculations, we have discovered for the first…

Topologically protected surface states of three-dimensional topological insulators provide a model framework for studying massless Dirac electrons in two dimensions. Usually a step on the surface of a topological insulator is treated as a…

Mesoscale and Nanoscale Physics · Physics 2019-01-14 N. I. Fedotov , S. V. Zaitsev-Zotov

The development of spin-based applications of topological insulators requires the knowledge and understanding of spin texture configuration maps as they change via gating in the vicinity of an isolated Dirac node. An isolated…

Mesoscale and Nanoscale Physics · Physics 2011-01-21 Su-Yang Xu , L. A. Wray , Y. Xia , F. von Rohr , Y. S. Hor , J. H. Dil , F. Meier , B. Slomski , J. Osterwalder , M. Neupane , H. Lin , A. Bansil , A. Fedorov , R. J. Cava , M. Z. Hasan