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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 energy-momentum relationship of electrons on the surface of an ideal "Hydrogen-Atom" Topological Insulator forms a cone - a Dirac cone, which, when warped and distorted (no longer described by the Dirac equation), can lead to unusual…

Mesoscale and Nanoscale Physics · Physics 2009-12-31 M. Z. Hasan , H. Lin , A. Bansil

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…

In this Letter we present scanning tunneling microscopy density-of-states measurements and electronic structure calculations of the topological insulator Bi2Se3. The measurements show significant background states in addition to the…

Mesoscale and Nanoscale Physics · Physics 2015-06-11 Megan Romanowich , Mal-Soon Lee , Duck-Young Chung , Jung-Hwan Song , S. D. Mahanti , Mercouri G. Kanatzidis , Stuart H. Tessmer

We have performed scanning tunneling microscopy and differential tunneling conductance ($dI/dV$) mapping for the surface of the three dimensional topological insulator Bi$_{2}$Se$_{3}$. The fast Fourier transformation applied to the $dI/dV$…

Mesoscale and Nanoscale Physics · Physics 2011-09-30 Sunghun Kim , M. Ye , K. Kuroda , Y. Yamada , E. E. Krasovskii , E. V. Chulkov , K. Miyamoto , M. Nakatake , T. Okuda , Y. Ueda , K. Shimada , H. Namatame , M. Taniguchi , A. Kimura

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

Electron scattering in the topological surface state (TSS) of the bulk-insulating topological insulator Bi$_{1.5}$Sb$_{0.5}$Te$_{1.7}$Se$_{1.3}$ was studied using quasiparticle interference observed by scanning tunneling microscopy. It was…

Mesoscale and Nanoscale Physics · Physics 2015-06-18 Sunghun Kim , Shunsuke Yoshizawa , Yukiaki Ishida , Kazuma Eto , Kouji Segawa , Yoichi Ando , Shik Shin , Fumio Komori

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…

Using femtosecond time- and angle- resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator Bi2Se3. We studied p-type Bi2Se3, in which the metallic Dirac surface state and bulk conduction…

We analyze the strong hexagonal warping of the Dirac cone of Bi$_2$Te$_3$ by angle-resolved photoemission. Along $\overline{\Gamma}$$\overline{\rm M}$, the dispersion deviates from a linear behavior meaning that the Dirac cone is warped…

Mesoscale and Nanoscale Physics · Physics 2015-04-08 J. Sánchez-Barriga , M. R. Scholz , E. Golias , E. Rienks , D. Marchenko , A. Varykhalov , L. V. Yashina , O. Rader

We introduce a dinstint approach to engineer a topologically protected surface state of a topological insulator. By covering the surface of a topological insulator, Bi2Te2Se, with a Bi monolayer film, the original surface state is…

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

We characterize the topological insulator Bi$_2$Se$_3$ using time- and angle- resolved photoemission spectroscopy. By employing two-photon photoemission, a complete picture of the unoccupied electronic structure from the Fermi level up to…

We report on microscopic tight-binding modeling of surface states in Bi$_2$Se$_3$ three-dimensional topological insulator, based on a sp$^3$ Slater-Koster Hamiltonian, with parameters calculated from density functional theory. The effect of…

Mesoscale and Nanoscale Physics · Physics 2014-11-04 A. Pertsova , C. M. Canali

Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control and…

Recently the doping of topological insulators has attracted significant interest as a potential route towards topological superconductivity. Because many experimental techniques lack sufficient surface sensitivity, however, a definite proof…

Topological insulators possess completely different spin-orbit coupled bulk and surface electronic spectra that are each predicted to exhibit exotic responses to light. Here we report time-resolved fundamental and second harmonic optical…

Mesoscale and Nanoscale Physics · Physics 2011-08-24 D. Hsieh , F. Mahmood , J. W. McIver , D. R. Gardner , Y. S. Lee , N. Gedik

Gapless surface states on topological insulators are protected from elastic scattering on non-magnetic impurities which makes them promising candidates for low-power electronic applications. However, for wide-spread applications, these…

Strongly Correlated Electrons · Physics 2013-07-04 Z. -H. Pan , E. Vescovo , A. V. Fedorov , G. D. Gu , T. Valla

The first experimental evidence is presented of the topological insulator state in PbBi$_{2}$Te$_{4}$. A single surface Dirac cone is observed by angle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation. Topological…

The topological insulators represent a unique state of matter where the bulk is insulating with an energy gap while the surface is metallic with a Dirac cone protected by the time reversal symmetry. These characteristics provide a venue to…