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The transport properties of the surface charge carriers of a three dimensional topological insulator under a terahertz (THz) field along with a resonant double barrier structure is theoretically analyzed within the framework of Floquet…

Mesoscale and Nanoscale Physics · Physics 2019-09-13 Puja Mondal , Sankalpa Ghosh , Manish Sharma

We investigated the electronic properties of the topological insulator Bi$_{2}$Te$_{3}$ by scanning tunneling microscopy and spectroscopy at low temperature. We obtained high-resolution quasiparticle interference data of the topological…

Nearly a decade after the discovery of topological insulators (TIs), the important task of identifying and characterizing their topological surface states through electrical transport experiments remains incomplete. The interpretation of…

Electron-electron interactions in topological p-n junctions consisting of vertically stacked topological insulators are investigated. n-type Bi2Te3 and p-type Sb2Te3 of varying relative thicknesses are deposited using molecular beam epitaxy…

We study theoretically the optical response of the surface states of a topological insulator, especially the generation of helicity-dependent direct current by circularly polarized light. Interestingly, the dominant current, due to an…

Materials Science · Physics 2013-05-29 Pavan Hosur

We study theoretically 2D HgTe/CdTe quantum well topological insulator (TI) illuminated by circularly polarized light with frequencies higher than the difference between the equilibrium Fermi level and the bottom of the conduction band (THz…

Mesoscale and Nanoscale Physics · Physics 2015-10-26 Vardan O. Kaladzhyan , Pavel P. Aseev , Sergey N. Artemenko

In high-performance solar cells based on polymeric semiconductors, the mechanism of photocarrier generation on $<100$-fs timescales is yet to be unravelled. In particular the dynamics of early-time electronic coupling between excitons on…

Topological insulators (TIs) represent a novel quantum state of matter, characterized by edge or surface-states, showing up on the topological character of the bulk wave functions. Allowing electrons to move along their surface, but not…

Advances in manipulating the structure of optical beams enable the study of interaction between structured light and low-dimensional semiconductor systems. We explore the photocurrents in two-dimensional systems excited by such…

Mesoscale and Nanoscale Physics · Physics 2024-03-08 A. A. Gunyaga , M. V. Durnev , S. A. Tarasenko

We report mid-infrared spectroscopy measurements of an electrostatically gated topological insulator, in which we observe several percent modulation of transmittance and reflectance of (Bi1-xSbx)2Te3 films as gating shifts the Fermi level.…

Mesoscale and Nanoscale Physics · Physics 2017-01-10 William S. Whitney , Victor W. Brar , Yunbo Ou , Yinming Shao , Artur R. Davoyan , D. N. Basov , Ke He , Qi-Kun Xue , Harry A. Atwater

Coherent control of optically-injected carrier distributions in single and bilayer graphene allows the injection of electrical currents. Using a tight-binding model and Fermi's golden rule, we derive the carrier and photocurrent densities…

Materials Science · Physics 2011-05-05 J. Rioux , Guido Burkard , J. E. Sipe

Two quintuple layers of strong topological insulator Bi2Se3 are coupled by a Bi bilayer in BiSe crystal. We investigated its electronic structure using angle resolved photoelectron spectroscopy to study its topological nature. Dirac like…

Materials Science · Physics 2023-10-31 H. Lohani , K. Majhi , R. Ganesan , S. Gonzalez , G. Di Santo , L. Petaccia , P. S. Anil Kumar , B. R. Sekhar

The electron dynamics of the topological surface state on Bi2Se3(111) is investigated by temperature-dependent angle-resolved photoemission. The electron-phonon coupling strength is determined in a spectral region for which only intraband…

Several proposed applications and exotic effects in topological insulators rely on the presence of helical Dirac states at the interface between a topological and a normal insulator. In the present work, we have used low-energy…

Materials Science · Physics 2013-11-20 M. H. Berntsen , O. Götberg , B. M. Wojek , O. Tjernberg

In this work, for the first time, a density functional theory (DFT) based comprehensive theoretical study is performed on the surface electronic properties of Bi2Se3 nanosheet in the presence of a surface capping layer as well as mechanical…

Materials Science · Physics 2024-12-10 Naresh Bahadursha , Banasree Sadhukhan , Tanay Nag , Swastik Bhattacharya , Sayan Kanungo

We investigate the ultrafast transient absorption spectrum of Bi2Se3 topological insulator. Bi2Se3 single crystal is grown through conventional solid-state reaction routevia self-flux method. The structural properties have been studied in…

Materials Science · Physics 2020-05-20 P. Sharma , D. Sharma , N. Vashistha , P. Rani , M. Kumar , S. S. Islam , V. P. S. Awana

Reversible control of the topological invariants from nontrivial to trivial states has fundamental implications for quantum information processors and spintronics, by realizing of an on/off switch for robust and dissipationless…

We perform linear and non-linear photon absorption calculations in topological insulator ultra-thin films on a substrate. Due to the unique band structure of the coupled topological surface states, novel features are observed for suitable…

Mesoscale and Nanoscale Physics · Physics 2013-11-18 Jing Wang , Hideo Mabuchi , Xiao-Liang Qi

We performed group theoretical investigation of symmetries of excitations in topological insulators \ce{Bi2Sb3}, \ce{Bi2Te3}, \ce{Bi2Se3} and \ce{Sb2Te3}, focusing on selection rules for optical processes. Electronic transitions of bulk…

Mesoscale and Nanoscale Physics · Physics 2012-05-04 Jian Li , Jiufeng J. Tu , Joseph L. Birman

We present a quantitative microscopic theory of the disorder- and phonon-induced coupling between surface and bulk states in topological insulator (TI) films. We find a simple structure for the surface-to-bulk scattering matrix elements and…

Strongly Correlated Electrons · Physics 2015-01-20 Kush Saha , Ion Garate