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High quality thin films of topological insulators (TI) such as Bi2Se3 have been successfully synthesized by molecular beam epitaxy (MBE). Although the surface of MBE films can be protected by capping with inert materials such as amorphous…

Materials Science · Physics 2014-12-10 Jixia Dai , Wenbo Wang , Matthew Brahlek , Nikesh Koirala , Maryam Salehi , Seongshik Oh , Weida Wu

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

We use real-time reflection high energy electron diffraction intensity oscillation to establish the Te-rich growth dynamics of topological insulator thin films of Bi2Te3 on Si(111) substrate by molecular beam epitaxy. In situ angle resolved…

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

Bulk superconductivity has been discovered in Tl_{0.6}Bi_{2}Te_{3}, which is derived from the topological insulator Bi2Te3. The superconducting volume fraction of up to 95% (determined from specific heat) with Tc of 2.28 K was observed. The…

Superconductivity · Physics 2016-08-17 Zhiwei Wang , A. A. Taskin , Tobias Froelich , Markus Braden , Yoichi Ando

We demonstrate the ability to reduce the carrier concentration of thin films of the topological insulator (TI) Bi2Se3 by utilizing a novel approach, namely non-volatile electrostatic gating via corona charging of electret polymers.…

Mesoscale and Nanoscale Physics · Physics 2018-04-11 R. M. Ireland , Liang Wu , M. Salehi , S. Oh , N. P. Armitage , H. E. Katz

The topological state that emerges at the surface of a topological insulator (TI) and at the TI-substrate interface are studied in metal-hBN-Bi2Se3 capacitors. By measuring the RF admittance of the capacitors versus gate voltage, we extract…

B and N K-edge x-ray absorption spectroscopy measurements have been performed on three BN thin films grown on Si substrates using ion-assisted pulsed laser deposition. Comparison of the films' spectra to those of several single-phase BN…

Condensed Matter · Physics 2007-05-23 A. Chaiken , L. J. Terminello , J. Wong , G. L. Doll , T. Sato

The tunability of the chemical potential for a wide range encompassing the Dirac point is important for many future devices based on topological insulators. Here we report a method to fabricate highly efficient top gates on epitaxially…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Fan Yang , A. A. Taskin , Satoshi Sasaki , Kouji Segawa , Yasuhide Ohno , Kazuhiko Matsumoto , Yoichi Ando

A topological insulator is a new state of matter, possessing gapless spin-locking surface states across the bulk band gap which has created new opportunities from novel electronics to energy conversion. However, the large concentration of…

Mesoscale and Nanoscale Physics · Physics 2013-03-08 Seung Sae Hong , Judy J. Cha , Desheng Kong , Yi Cui

Using first-principles calculations and Boltzmann theory, we explore the feasibility to maximize the thermoelectric figure of merit (ZT) of topological insulator Bi2Te3 films in the few-quintuple layer regime. We discover that the delicate…

Mesoscale and Nanoscale Physics · Physics 2016-06-09 Jinghua Liang , Long Cheng , Jie Zhang , Huijun Liu , Zhenyu Zhang

Understanding the spin-texture behavior of boundary modes in ultrathin topological insulator films is critically essential for the design and fabrication of functional nano-devices. Here by using spin-resolved photoemission spectroscopy…

We report a detailed study of surface and interface properties of pulsed-laser deposited NiMnSb films on Si (100) substrate as a function of film thickness. As the thickness of films is reduced below 35 nm formation of a porous layer is…

We report on very high enhancement of thin layer's absorption through band-engineering of a photonic crystal structure. We realized amorphous silicon (aSi) photonic crystals, where slow light modes improve absorption efficiency. We show…

Bi2Se3 is theoretically predicted1 2and experimentally observed2,3 to be a three dimensional topological insulator. For possible applications, it is important to understand the electronic structure of the planar device. In this work,…

We report on the effect of exposure to atmospheric conditions on the THz conductivity of thin films of the topological insulator Bi$_2$Se$_3$. We find: 1) two contributions of mobile charge carriers to the THz conductivity immediately after…

Strongly Correlated Electrons · Physics 2013-09-05 R. Valdés Aguilar , L. Wu , A. V. Stier , L. S. Bilbro , M. Brahlek , N. Bansal , S. Oh , N. P. Armitage

Quantum transport measurements including the Altshuler-Aronov-Spivak (AAS) and Aharonov-Bohm (AB) effects, universal conductance fluctuations (UCF), and weak anti-localization (WAL) have been carried out on epitaxial Bi thin films ($10-70$…

Mesoscale and Nanoscale Physics · Physics 2017-07-07 Kai Zhu , Lin Wu , Xinxin Gong , Shunhao Xiao , Shiyan Li , Xiaofeng Jin , Mengyu Yao , Dong Qian , Meng Wu , Ji Feng , Qian Niu , Fernando de Juan , Dung-Hai Lee

Atomically flat thin films of topological insulator Bi2Se3 have been grown on double-layer graphene formed on 6H-SiC(0001) substrate by molecular beam epitaxy. By a combined study of reflection high energy electron diffraction and scanning…

We use first-principles simulations to investigate the topological properties of Bi$_2$Se$_3$ thin films deposited on amorphous SiO2, Bi$_2$Se$_3$/a-SiO$_2$, which is a promising substrate for topological insulator (TI) based device…

Materials Science · Physics 2016-12-21 I. S. S. de Oliveira , W. L. Scopel , R. H. Miwa

Recently, there have been intense efforts in searching for new topological insulator (TI) materials. Based on first-principles calculations, we find that all the ultrathin Bi (111) films are characterized by a nontrivial Z2 number…

Materials Science · Physics 2012-12-21 Zheng Liu , Chao-Xing Liu , Yong-Shi Wu , Wen-Hui Duan , Feng Liu , Jian Wu