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Search for New Topological Materials

Speaker: 
Hsin Lin (Department of Physics, Northeastern University, USA)
Date: 
Tue, 10/07/2012 - 12:00pm to 1:00pm
Location: 
S13-02-14 (Physics Resource Room, NUS)
Event Type: 
Seminars

Abstract

Recent development of topological band theory combined with the predictive power of first-principles calculations has led to discovery of new states of quantum matter as well as their material realization. These topological materials are distinguished by unique physical properties. Due to the time-reversal symmetry, the topological insulators host back-scattering-free spin-polarized surface states that enables viable applications in spintronics. Topological superconductors offer the opportunity to observe Majorana fermions which is a first step towards fault-tolerant quantum computation. Topological materials are interesting from both a fundamental physics and a practical applications point of view. While several families of topological insulators have already been found, the intense world-wide search for new classes of topological materials continues unabated. This interest is driven by the need for materials with greater structural flexibility and tunability to enable viable applications in spintronics and quantum computing. We have used first-principles band theory computations in combination with angle-resolved photoemission experiments to successfully predict many new classes of topologically interesting materials, including Bi2Se3 series, the ternary half-Heusler compounds, thallium-based chalcogenides, Li2AgSb-class, GenBi2mTe3m+n families, quaternary chalcogenides and famatinites as well as the first material realization of topological crystalline insulator in (Pb,Sn)Te class.[1-3] The topological phase transition of silicene and TlBi(Se,S)2 and the properties of the surface states will be demonstrated. [4,5]

 

[1] Y. Xia, D. Qian, D. Hsieh, L.Wray, A. Pal, H. Lin, A. Bansil, D. Grauer, Y. S. Hor, R. J. Cava, and M. Z. Hasan, Nature Physics 5, 398 (2009).
[2] H. Lin, L. A. Wray, Y. Xia. S. Y. Xu, S. Jia, R. J. Cava, A. Bansil, and M. Z. Hasan, Nature Materials 9, 546 (2010).
[3] H. Lin, R. S. Markiewicz, L. A. Wray, L. Fu, M. Z. Hasan, Physical Review Letters 105, 036404 (2010).
[4] S. Y. Xu, Y. Xia, L. A. Wray, S. Jia, F. Meier, J. H. Dil, J. Osterwalder, B. Slomski, A. Bansil, H. Lin, R. J. Cava, and M. Z. Hasan, Science 332, 560 (2011).
[5] S. Y. Xu, M. Neupane, Chang Liu, L. A. Wray, Duming M. Zhang, A. Richardella, Nasser Alidoust, M. Leandersson, T. Balasubramanian, J. Sanchez-Barriga, O. Rader, G. Landolt, Bartosz Slomski, J. Dil, Tay-Rong Chang, Horng-Tay Jeng, J. Osterwalder , H. Lin, A. Bansil, N. Samarth, M. Z. Hasan, Nature Physics, in press (2012).

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