Please use this identifier to cite or link to this item: https://hdl.handle.net/10356/85511
 Title: Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells Authors: Song, ZhigangBose, SumantaFan, WeijunZhang, Dao HuaZhang, Yan YangLi, Shu Shen Keywords: Topological insulatorQuantum spin Hall effect Issue Date: 2017 Source: Song, Z., Bose, S., Fan, W., Zhang, D. H., Zhang, Y. Y., & Li, S. S. (2017). Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells. New Journal of Physics, 19, 073031-. Series/Report no.: New Journal of Physics Abstract: Quantum spin Hall (QSH) effect, a fundamentally new quantum state of matter and topological phase transitions are characteristics of a kind of electronic material, popularly referred to as topological insulators (TIs). TIs are similar to ordinary insulator in terms of their bulk bandgap, but have gapless conducting edge-states that are topologically protected. These edge-states are facilitated by the time-reversal symmetry and they are robust against nonmagnetic impurity scattering. Recently, the quest for new materials exhibiting non-trivial topological state of matter has been of great research interest, as TIs find applications in new electronics and spintronics and quantum-computing devices. Here, we propose and demonstrate as a proof-of-concept that QSH effect and topological phase transitions can be realized in ${\mathrm{InN}}_{x}{\mathrm{Bi}}_{y}{\mathrm{Sb}}_{1-x-y}$/InSb semiconductor quantum wells (QWs). The simultaneous incorporation of nitrogen and bismuth in InSb is instrumental in lowering the bandgap, while inducing opposite kinds of strain to attain a near-lattice-matching conducive for lattice growth. Phase diagram for bandgap shows that as we increase the QW thickness, at a critical thickness, the electronic bandstructure switches from a normal to an inverted type. We confirm that such transition are topological phase transitions between a traditional insulator and a TI exhibiting QSH effect—by demonstrating the topologically protected edge-states using the bandstructure, edge-localized distribution of the wavefunctions and edge-state spin-momentum locking phenomenon, presence of non-zero conductance in spite of the Fermi energy lying in the bandgap window, crossover points of Landau levels in the zero-mode indicating topological band inversion in the absence of any magnetic field and presence of large Rashba spin-splitting, which is essential for spin-manipulation in TIs. URI: https://hdl.handle.net/10356/85511http://hdl.handle.net/10220/43736 ISSN: 1367-2630 DOI: 10.1088/1367-2630/aa795c Rights: © 2017 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. Original content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Fulltext Permission: open Fulltext Availability: With Fulltext Appears in Collections: EEE Journal Articles

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