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2 results on '"Wen-Yu Shan"'

1. Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit

Author

Qian Niu, Cui-Zu Chang, Xiao-Liang Qi, Ke He, Shou-Cheng Zhang, Xucun Ma, Xi Chen, Can-Li Song, Zhong Fang, Jin-Feng Jia, Lili Wang, Qi-Kun Xue, Yi Zhang, Xi Dai, Wen-Yu Shan, and Shun-Qing Shen

Subjects
Condensed Matter::Quantum Gases, Physics, Condensed Matter - Materials Science, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed matter physics, Topological degeneracy, Crossover, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, General Physics and Astronomy, Condensed Matter::Materials Science, Gapless playback, Condensed Matter::Superconductivity, Topological insulator, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Topological order, Condensed Matter::Strongly Correlated Electrons, Limit (mathematics), Thin film, Surface states
Abstract

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, thickness dependent band structure of molecular beam epitaxy grown ultrathin films of Bi2Se3 is investigated by in situ angle-resolved photoemission spectroscopy. An energy gap is observed for the first time in the topologically protected metallic surface states of bulk Bi2Se3 below the thickness of six quintuple layers, due to the coupling between the surface states from two opposite surfaces of the Bi2Se3 film. The gapped surface states exhibit sizable Rashba-type spin-orbit splitting, due to breaking of structural inversion symmetry induced by SiC substrate. The spin-splitting can be controlled by tuning the potential difference between the two surfaces., Comment: 17 pages, 3 figures,1 table

Published
2010

2. Crossover of the three-dimensional topological insulator Bi2Se3 to the two-dimensional limit.

Author

Yi Zhang, Ke He, Cui-Zu Chang, Can-Li Song, Li-LiWang, Xi Chen, Jin-Feng Jia, Zhong Fang, Xi Dai, Wen-Yu Shan, Shun-Qing Shen, Qian Niu, Xiao-Liang Qi, Shou-Cheng Zhang, Xu-Cun Ma, and Qi-Kun Xue

Subjects
BISMUTH compounds, PHOTOEMISSION, MOLECULAR beam epitaxy, THIN films, BAND gaps
Abstract

A topological insulator is a new state of quantum matter that is characterized by a finite energy gap in the bulk and gapless modes flowing along the boundaries that are robust against disorder scattering. The topological protection of the surface state could be useful for both low-power electronics and error-tolerant quantum computing. For a thin slab of three-dimensional topological insulator, the boundary modes from the opposite surfaces may be coupled by quantum tunnelling, so that a small, thickness-dependent gap is opened up. Here we report such results from angle-resolved photoemission spectroscopy on Bi2Se3 films of various thicknesses grown by molecular beam epitaxy. The energy gap opening is clearly seen when the thickness is below six quintuple layers. The gapped surface states also exhibit sizeable Rashba-type spin–orbit splitting because of the substrate-induced potential difference between the two surfaces. The tunable gap and the spin–orbit coupling make these topological thin films ideal for electronic and spintronic device applications. [ABSTRACT FROM AUTHOR]

Published
2010
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