Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells
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 ga...
| Main Authors: | , , , , , |
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| Format: | Journal Article |
| Language: | English |
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2017
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| Online Access: | https://hdl.handle.net/10356/85511 http://hdl.handle.net/10220/43736 |
| _version_ | 1824454962074091520 |
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| author | Song, Zhigang Bose, Sumanta Fan, Weijun Zhang, Dao Hua Zhang, Yan Yang Li, Shu Shen |
| author2 | School of Electrical and Electronic Engineering |
| author_facet | School of Electrical and Electronic Engineering Song, Zhigang Bose, Sumanta Fan, Weijun Zhang, Dao Hua Zhang, Yan Yang Li, Shu Shen |
| author_sort | Song, Zhigang |
| collection | NTU |
| description | 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. |
| first_indexed | 2025-02-19T03:30:38Z |
| format | Journal Article |
| id | ntu-10356/85511 |
| institution | Nanyang Technological University |
| language | English |
| last_indexed | 2025-02-19T03:30:38Z |
| publishDate | 2017 |
| record_format | dspace |
| spelling | ntu-10356/855112020-03-07T13:57:27Z Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells Song, Zhigang Bose, Sumanta Fan, Weijun Zhang, Dao Hua Zhang, Yan Yang Li, Shu Shen School of Electrical and Electronic Engineering Centre for OptoElectronics and Biophotonics LUMINOUS! Centre of Excellence for Semiconductor Lighting & Displays Topological insulator Quantum spin Hall effect 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. ASTAR (Agency for Sci., Tech. and Research, S’pore) MOE (Min. of Education, S’pore) EDB (Economic Devt. Board, S’pore) Published version 2017-09-12T09:01:14Z 2019-12-06T16:05:13Z 2017-09-12T09:01:14Z 2019-12-06T16:05:13Z 2017 Journal Article 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-. 1367-2630 https://hdl.handle.net/10356/85511 http://hdl.handle.net/10220/43736 10.1088/1367-2630/aa795c en New Journal of Physics © 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. 11 p. application/pdf |
| spellingShingle | Topological insulator Quantum spin Hall effect Song, Zhigang Bose, Sumanta Fan, Weijun Zhang, Dao Hua Zhang, Yan Yang Li, Shu Shen Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells |
| title | Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells |
| title_full | Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells |
| title_fullStr | Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells |
| title_full_unstemmed | Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells |
| title_short | Quantum spin Hall effect and topological phase transition in InNxBiySb1−x−y/InSb quantum wells |
| title_sort | quantum spin hall effect and topological phase transition in innxbiysb1 x y insb quantum wells |
| topic | Topological insulator Quantum spin Hall effect |
| url | https://hdl.handle.net/10356/85511 http://hdl.handle.net/10220/43736 |
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