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The zero gap surface states of a 3D-topological insulator host highly mobile Dirac fermions with spin locked to the momentum. The high mobility attributed to absence of back scattering is reduced in presence of impurities on the surface. In…

Mesoscale and Nanoscale Physics · Physics 2015-05-20 Parijat Sengupta , Enrico Bellotti

The observation of helical surface states in Bi-based three-dimensional topological insulators has been a challenge since their theoretical prediction. The main issue raises when the Fermi level shifts deep into the bulk conduction band due…

Mesoscale and Nanoscale Physics · Physics 2021-02-18 Shaham Jafarpisheh , An Ju , Kevin Janßen , Takashi Taniguchi , Kenji Watanabe , Christoph Stampfer , Bernd Beschoten

We numerically demonstrate a practical means of systematically controlling topological transport on the surface of a three dimensional topological insulator, by introducing strong disorder in a layer of depth $d$ extending inward from the…

Mesoscale and Nanoscale Physics · Physics 2015-06-17 Vincent Sacksteder , Tomi Ohtsuki , Koji Kobayashi

We demonstrate theoretically that most of the observed transport properties of graphene sheets at zero magnetic field can be explained by scattering from charged impurities. We find that, contrary to common perception, these properties are…

Mesoscale and Nanoscale Physics · Physics 2008-01-14 Shaffique Adam , E. H. Hwang , Victor Galitski , S. Das Sarma

A density functional theory based two-terminal scattering formalism that includes spin-orbit coupling and spin non-collinearity is described. An implementation using tight-binding muffin-tin orbitals combined with extensive use of sparse…

Mesoscale and Nanoscale Physics · Physics 2018-06-15 Anton A. Starikov , Yi Liu , Zhe Yuan , Paul J. Kelly

The lifetime of electrons on edge states of a two-dimensional topological insulator against the background of an allowed two-dimensional band has been determined. It has been shown that this time in the case of scattering on Coulomb…

Mesoscale and Nanoscale Physics · Physics 2019-06-26 M. M. Mahmoodian , M. V. Entin

A theory is developed for the density and temperature dependent carrier conductivity in doped three-dimensional (3D) Dirac materials focusing on resistive scattering from screened Coulomb disorder due to random charged impurities (e.g.,…

Mesoscale and Nanoscale Physics · Physics 2015-01-20 S. Das Sarma , E. H. Hwang , Hongki Min

We fabricate electric double-layer field-effect transistor (EDL-FET) devices on mechanically exfoliated few-layer graphene. We exploit the large capacitance of a polymeric electrolyte to study the transport properties of three, four and…

Mesoscale and Nanoscale Physics · Physics 2017-01-11 E. Piatti , S. Galasso , M. Tortello , J. R. Nair , C. Gerbaldi , D. Daghero , M. Bruna , S. Borini , R. S. Gonnelli

Carrier transport in gated 2D graphene monolayers is theoretically considered in the presence of scattering by random charged impurity centers with density $n_i$. Excellent quantitative agreement is obtained (for carrier density $n >…

Mesoscale and Nanoscale Physics · Physics 2007-10-09 E. H. Hwang , S. Adam , S. Das Sarma

We theoretically calculate and compare the single-particle relaxation time ($\tau_s$) defining quantum level broadening and the transport scattering time ($\tau_t$) defining Drude conductivity in 2D graphene layers in the presence of…

Mesoscale and Nanoscale Physics · Physics 2008-05-12 E. H. Hwang , S. Das Sarma

Spatially controlling the Fermi level of topological insulators and keeping its electronic states stable are indispensable processes to put this material into practical use for semiconductor spintronics devices. So far, however, such a…

In this work we study the topologically protected states of the Sb(111) surface by using ab-initio transport theory. In the presence of a strong surface perturbation we obtain standing-wave states resulting from the superposition of…

Mesoscale and Nanoscale Physics · Physics 2013-06-11 Awadhesh Narayan , Ivan Rungger , Stefano Sanvito

The fate of electric dipoles inside a Fermi sea is an old issue, yet poorly-explored. Sr$_{1-x}$Ca$_x$TiO$_{3}$ hosts a robust but dilute ferroelectricity in a narrow ($0.002<x<0.02$) window of substitution. This insulator becomes metallic…

Chiral surface states in topological insulators are robust against interactions, non-magnetic disorder and localization, yet topology does not yield protection in transport. This work presents a theory of interacting topological insulators…

Mesoscale and Nanoscale Physics · Physics 2015-03-19 Dimitrie Culcer

Using THz spectroscopy in external magnetic fields we investigate the low-temperature charge dynamics of strained HgTe, a three dimensional topological insulator. From the Faraday rotation angle and ellipticity a complete characterization…

Strongly Correlated Electrons · Physics 2013-03-27 A. M. Shuvaev , G. V. Astakhov , G. Tkachov , C. Brüne , H. Buhmann , L. W. Molenkamp , A. Pimenov

Three-dimensional topological insulators of finite thickness can show the quantum Hall effect (QHE) at the filling factor $\nu=0$ under an external magnetic field if there is a finite potential difference between the top and bottom…

Mesoscale and Nanoscale Physics · Physics 2015-04-14 Takahiro Morimoto , Akira Furusaki , Naoto Nagaosa

Topological insulators are guaranteed to support metallic surface states on an insulating bulk, and one should thus expect that the electronic transport in these materials is dominated by the surfaces states. Alas, due to the high remaining…

We investigate the itinerant ferromagnetism using a diluted spin-fermion model, derived from a repulsive Hubbard model, where itinerant fermions are coupled antiferromagnetically to auxiliary fields in a three-dimensional simple cubic…

Strongly Correlated Electrons · Physics 2022-01-31 Sourav Chakraborty , Sandip Halder , Kalpataru Pradhan

We theoretically study transport properties of a two-dimensional electron system on a hydrogen-passivated Si(111) surface in the field-effect-transistor (FET) configuration. We calculate the density and temperature dependent mobility and…

Materials Science · Physics 2009-11-11 E. H. Hwang , S. Das Sarma

It is shown that clustering of charged impurities on graphene can suppress their contribution to the resistivity by a large factor of about the number of impurities per cluster, while leaving the density dependence unchanged. If the cluster…

Mesoscale and Nanoscale Physics · Physics 2009-05-25 M. I. Katsnelson , F. Guinea , A. K. Geim