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A key feature of topological insulators is the robustness of the electron energy spectrum. At a surface of a topological insulator, Dirac point is protected by the characteristic symmetry of the system. The breaking of the symmetry opens a…

Mesoscale and Nanoscale Physics · Physics 2016-12-21 S. Stagraczynski , L. Chotorlishvili , V. K. Dugaev , C. -L. Jia , A. Ernst , A. Komnik , J. Berakdar

We develop an effective bulk model with a topological boundary condition to study the surface states of topological insulators. We find that the Dirac point energy, the band curvature and the spin texture of surface states are crystal…

Mesoscale and Nanoscale Physics · Physics 2013-05-01 Fan Zhang , C. L. Kane , E. J. Mele

We consider spin-polarized transport in a quantum spin Hall antidot system coupled to normal leads. Due to the helical nature of the conducting edge states, the screening potential at the dot region becomes spin dependent without external…

Mesoscale and Nanoscale Physics · Physics 2014-09-04 Sun-Yong Hwang , Rosa Lopez , Minchul Lee , David Sanchez

Both the theoretical and experimental discovery of single-Dirac-cone topological-insulator-class was reported at arXiv:0812.2078 (2008) [Y. Xia et.al., Nature Physics 5, 398-402 (2009)…

Magnetic devices are a leading contender for implementing memory and logic technologies that are nonvolatile, that can scale to high density and high speed, and that do not suffer wear-out. However, widespread applications of magnetic…

Mesoscale and Nanoscale Physics · Physics 2015-06-18 A. R. Mellnik , J. S. Lee , A. Richardella , J. L. Grab , P. J. Mintun , M. H. Fischer , A. Vaezi , A. Manchon , E. -A. Kim , N. Samarth , D. C. Ralph

When electrons are subject to a large external magnetic field, the conventional charge quantum Hall effect \cite{Klitzing,Tsui} dictates that an electronic excitation gap is generated in the sample bulk, but metallic conduction is permitted…

Mesoscale and Nanoscale Physics · Physics 2009-10-14 D. Hsieh , D. Qian , L. Wray , Y. Xia , Y. S. Hor , R. J. Cava , M. Z. Hasan

Three-dimensional (3D) topological insulators (TIs) are known to carry 2D Dirac-like topological surface states in which spin-momentum locking prohibits backscattering. When thinned down to a few nanometers, the hybridization between the…

We consider thermoelectric transport properties of the edge states of a two dimensional topological insulator in a double quantum point contact geometry coupled to two thermally biased reservoirs. Both spin-preserving and spin-flipping…

Mesoscale and Nanoscale Physics · Physics 2016-04-13 Flavio Ronetti , Luca Vannucci , Giacomo Dolcetto , Matteo Carrega , Maura Sassetti

We investigate the charge conductivity and current-induced spin polarization on the surface state of a three-dimensional topological insulator by including the hexagonal warping effect of Fermi surface both in classical and quantum…

Mesoscale and Nanoscale Physics · Physics 2011-11-01 C. M. Wang , F. J. Yu

We show that in the new topological-insulator compound Bi_{1.5}Sb_{0.5}Te_{1.7}Se_{1.3} one can achieve a surfaced-dominated transport where the surface channel contributes up to 70% of the total conductance. Furthermore, it was found that…

Materials Science · Physics 2011-07-28 A. A. Taskin , Zhi Ren , Satoshi Sasaki , Kouji Segawa , Yoichi Ando

Topological insulators host spin-polarized surface states born out of the energetic inversion of bulk bands driven by the spin-orbit interaction. Here we discover previously unidentified consequences of band-inversion on the surface…

Topological insulators have surface states with a remarkable helical spin structure, with promising prospects for applications in spintronics. Strategies for generating spin polarized currents, such as the use of magnetic contacts and…

Mesoscale and Nanoscale Physics · Physics 2014-05-21 Rodrigo A. Muniz , J. E. Sipe

Spin-momentum helical locking is one of the most important properties of the nontrivial topological surface states (TSS) in 3D topological insulators (TI). It underlies the iconic topological protection (suppressing elastic backscattering)…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Jifa Tian , Isaac Childres , Helin Cao , Shen Tian , Ireneusz Miotkowski , Yong P. Chen

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 characterized by Dirac cone surface states with electron spins aligned in the surface plane and perpendicular to their momenta. Recent theoretical and experimental work implied that this specific spin texture…

We achieve the enhancement of circular photogalvanic effect arising from the photo-injection of spins in topological insulator thin films by tuning the Fermi level ($E_{\rm F}$). A series of (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ thin films were…

Materials Science · Physics 2016-02-09 K. N. Okada , N. Ogawa , R. Yoshimi , A. Tsukazaki , K. S. Takahashi , M. Kawasaki , Y. Tokura

In recent years, a class of solid state materials, called three-dimensional topological insulators, has emerged. In the bulk, a topological insulator behaves like an ordinary insulator with a band gap. At the surface, conducting gapless…

Materials Science · Physics 2015-03-27 Christoph Kastl , Christoph Karnetzky , Helmut Karl , Alexander W. Holleitner

We performed high-resolution spin- and angle-resolved photoemission spectroscopy studies of the electronic structure and the spin texture on the surface of Bi$_2$Se$_3$, a model topological insulator. By tuning the photon energy, we found…

Strongly Correlated Electrons · Physics 2011-09-28 Z. -H. Pan , E. Vescovo , A. V. Fedorov , D. Gardner , Y. S. Lee , S. Chu , G. D. Gu , T. Valla

Surfaces of topological insulators host a new class of states with Dirac dispersion and helical spin texture. Potential quantum computing and spintronic applications using these states require manipulation of their electronic properties at…

Mesoscale and Nanoscale Physics · Physics 2015-05-30 Haim Beidenkopf , Pedram Roushan , Jungpil Seo , Lindsay Gorman , Ilya Drozdov , Yew San Hor , R. J. Cava , Ali Yazdani

We show that the interplay between chiral tunneling and spin-momentum locking of helical surface states leads to spin amplification and filtering in a 3D Topological Insulator (TI). Chiral tunneling across a TI pn junction allows normally…

Mesoscale and Nanoscale Physics · Physics 2015-03-23 K. M. Masum Habib , Redwan N. Sajjad , Avik W. Ghosh