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We present an infrared magneto-optical study of the highly thermoelectric narrow-gap semiconductor Bi$_2$Se$_3$. Far-infrared and mid-infrared (IR) reflectance and transmission measurements have been performed in magnetic fields oriented…

Strongly Correlated Electrons · Physics 2010-07-05 A. D. LaForge , A. Frenzel , B. C. Pursley , Tao Lin , Xinfei Liu , Jing Shi , D. N. Basov

Ultra-thin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak Van der Waals interaction between adjacent quintuple…

Mesoscale and Nanoscale Physics · Physics 2010-08-16 Seung Sae Hong , Worasom Kundhikanjana , Judy J. Cha , Keji Lai , Desheng Kong , Stefan Meister , Michael A. Kelly , Zhi-Xun Shen , Yi Cui

Due to the strong quantum confinement effect, few-layer {\gamma}-InSe exhibits a layer-dependent bandgap, spanning the visible and near infrared regions, and thus recently draws tremendous attention. As a two-dimensional material, the…

Mesoscale and Nanoscale Physics · Physics 2018-03-20 Chaoyu Song , Fengren Fan , Ningning Xuan , Shenyang Huang , Guowei Zhang , Chong Wang , Zhengzong Sun , Hua Wu , Hugen Yan

Bismuth antimony alloys (Bi$_x$Sb$_{1-x}$) provide a tuneable materials platform to study topological transport and spin-polarized surface states resulting from the nontrivial bulk electronic structure. In the two-dimensional limit, it is a…

Bismuth selenide, a benchmark topological insulator, grows in a trigonal structure at ambient conditions and exhibits a number of enticing properties related to the formation of Dirac surface states. Besides this polytype, a metastable…

Many applications for topological insulators (TIs) as well as new phenomena require devices with reduced dimensions. While much progress has been made to realize thin films of TIs with low bulk carrier density, nanostructures have not yet…

We present a new method to obtain topological insulator Bi$_2$Se$_3$ thin films with a centimeter large lateral length. To produce amorphous Bi$_2$Se$_3$ thin films we have used a sequential flash-evaporation method at room temperature.…

Materials Science · Physics 2015-06-23 J. Barzola-Quiquia , T. Lehmann , M. Stiller , D. Spemann , P. Esquinazi , P. Häussler

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

The evidence for proximity-induced superconductivity in heterostructures of topological insulators and high-Tc cuprates has been intensely debated. We use molecular beam epitaxy to grow thin films of topological insulator Bi2Te3 on a…

Topologically protected surface states have garnered significant attention due to their robustness against perturbations and potential applications in optoelectronics. Bi2 Bi2Se3 is a topological semimetal composed of a 2D bismuthene sheet…

Ultrathin (~3 quintuple layer) field-effect transistors (FETs) of topological insulator Bi2Se3 are prepared by mechanical exfoliation on 300nm SiO2/Si susbtrates. Temperature- and gate-voltage dependent conductance measurements show that…

Mesoscale and Nanoscale Physics · Physics 2012-01-19 Sungjae Cho , Nicholas P. Butch , Johnpierre Paglione , Michael S. Fuhrer

We use angle-resolved photoemission spectroscopy to study non-trivial surface state in psuedobinary Bi2Se0.6Te2.3 topological insulator. We show that unlike previously studied binaries, this is an intrinsic topological insulator with…

Strongly Correlated Electrons · Physics 2015-06-04 Rui Jiang , Lin-Lin Wang , Mianliang Huang , R. S. Dhaka , Duane D. Johnson , Thomas A. Lograsso , Adam Kaminski

Insulating substrates are crucial for electrical transport study and room temperature application of topological insulator films at thickness of only several nanometers. High quality quantum well films of Bi2Se3, a typical three-dimensional…

Mesoscale and Nanoscale Physics · Physics 2011-08-24 Cui-Zu Chang , Ke He , Min-Hao Liu , Zuo-Cheng Zhang , Xi Chen , Li-Li Wang , Xu-Cun Ma , Ya-Yu Wang , Qi-Kun Xue

We measure gate-tuned thermoelectric power of mechanically exfoliated Bi2Se3 thin films in the topological insulator regime. The sign of the thermoelectric power changes across the charge neutrality point as the majority carrier type…

Mesoscale and Nanoscale Physics · Physics 2015-03-12 Dohun Kim , Paul Syers , Nicholas P. Butch , Johnpierre Paglione , Michael S. Fuhrer

Thin (6-7 quintuple layer) topological insulator Bi2Se3 quantum dot devices are demonstrated using ultrathin (2~4 quintuple layer) Bi2Se3 regions to realize semiconducting barriers which may be tuned from Ohmic to tunneling conduction via…

Mesoscale and Nanoscale Physics · Physics 2012-01-19 Sungjae Cho , Dohun Kim , Paul Syers , Nicholas P. Butch , Johnpierre Paglione , Michael S. Fuhrer

Topological insulator films are promising materials for optoelectronics due to a strong optical absorption and a thickness dependent band gap of the topological surface states. They are superior candidates for photodetector applications in…

Mesoscale and Nanoscale Physics · Physics 2018-09-11 Mathias Rosdahl Brems , Jens Paaske , Anders Mathias Lunde , Morten Willatzen

This letter reports the modification of magnetism in a magnetic insulator Y3Fe5O12 thin film by topological surface states (TSS) in an adjacent topological insulator Bi2Se3 thin film. Ferromagnetic resonance measurements show that the TSS…

Topological insulators represent a paradigm shift in surface physics. The most extensively studied Bi$_2$Se$_3$-type topological insulators exhibit layered structures, wherein neighboring layers are weakly bonded by van der Waals…

Materials Science · Physics 2016-01-22 Can Li , Torben Winzer , Aron Walsh , Binghai Yan , Catherine Stampfl , Aloysius Soon

We have performed angle-resolved photoemission spectroscopy on (PbSe)5(Bi2Se3)3m, which forms a natural multilayer heterostructure consisting of a topological insulator (TI) and an ordinary insulator. For m = 2, we observed a gapped…

Mesoscale and Nanoscale Physics · Physics 2015-06-05 K. Nakayama , K. Eto , Y. Tanaka , T. Sato , S. Souma , T. Takahashi , Kouji Segawa , Yoichi Ando

Topological insulators are new class of quantum materials, which have insulating energy gaps in bulk, but exhibit gapless edge states or surface states that are protected by time-reversal symmetry at boundary. It was theoretically predicted…

Mesoscale and Nanoscale Physics · Physics 2018-03-07 G. H. Cao , H. J. Liu , J. H. Liang , L. Cheng , D. D. Fan , Z. Y. Zhang