Browsing by Author "Hsu, Chang-Shun"

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Insulating state to quantum Hall-like state transition in a spin-orbit-coupled two-dimensional electron system
(2014-07-07)
Lo, Shun-Tsung
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Hsu, Chang-Shun
;
Lin, Y. M.
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Lin, S-D
;
Lee, C. P.
We study interference and interactions in an InAs/InAsSb two-dimensional electron system. In such a system, spin-orbit interactions are shown to be strong, which result in weak antilocalization (WAL) and thereby positive magnetoresistance around zero magnetic field. After suppressing WAL by the magnetic field, we demonstrate that classical positive magnetoresistance due to spin-orbit coupling plays a role. With further increasing the magnetic field, the system undergoes a direct insulator-quantum Hall transition. By analyzing the magnetotransport behavior in different field regions, we show that both electron-electron interactions and spin-related effects are essential in understanding the observed direct transition. (C) 2014 AIP Publishing LLC.
Probing the coexistence of semiclassical transport and localization in a two-dimensional electron gas using microwave radiation
(2013-03-01)
Hsu, Chang-Shun
;
Kannan, E. S.
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Portal, J-C.
;
Liang, C. -T.
;
Huang, C. F.
We have performed magnetoresistance measurements on a GaAs/AlGaAs two-dimensional electron gas under microwave heating. Both the magneto-oscillations and magnetoresistance minima are used as electron thermometers to determine the electron effective temperature T-e. When there is no clear cyclotron gap, it is found that T-e determined from these two methods can be substantially different such that we can still distinguish localized electrons from the semiclassical conducting ones. The almost constant T-e obtained from the magnetoresistance minima reveals the survived equivalence between different Landau-band tails under insufficient localization. (C) 2012 Elsevier Ltd. All rights reserved.