Browsing by Author "Wang, LY"

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dc spin current generation in a Rashba-type quantum channel
(2006-02-01)
Wang, LY
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Tang, CS
;
Chu, CS
;
電子物理學系
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Department of Electrophysics
We propose and demonstrate theoretically that resonant inelastic scattering (RIS) can play an important role in dc spin current generation. The RIS makes it possible to generate dc spin current via a simple gate configuration: a single finger gate that locates atop and orients transversely to a quantum channel in the presence of Rashba spin-orbit interaction. The ac-biased finger gate gives rise to a time variation in the Rashba coupling parameter, which causes spin-resolved RIS and, subsequently, contributes to the dc spin current. The spin current depends on both the static and the dynamic parts in the Rashba coupling parameter, alpha(0) and alpha(1), respectively, and is proportional to alpha(0)alpha(2)(1). The proposed gate configuration has the added advantage that no dc charge current is generated. Our study also shows that the spin current generation can be enhanced significantly in a double finger-gate configuration.
Effects of an elastic scatterer on the DC spin current generation in a Rashba-type quantum channel
(2006-05-01)
Wang, LY
;
Tang, CS
;
Chu, CS
;
電子物理學系
;
Department of Electrophysics
In this work, we consider a Rashba-type quantum channel (RQC) consisting of one AC-biased finger-gates (FG) that orient perpendicularly and located above the RQC. Such an AC-biased FG gives rise to a local time-modulation in the Rashba coupling parameter, and is shown recently to generate a DC spin current [L.Y. Wang, C.S. Tang, C.S. Chu, Cond-mat/0409291, 2004]. No charge current, however, is generated in this configuration. We explore the robustness of such DC spin current generation against elastic scattering in the RQC. The effect of backscattering is studied by introducing a static barrier that is uniform in the transverse dimension. The effects of both backscattering and subband mixing is studied by introducing a static partial-barrier that is spatially localized and non-uniform in the transverse dimension. In addition, we compare the cases of attractive and repulsive partial-barriers. It is found that attractive partial-barrier gives rise to additional DC spin current structures due to resonant inter-subband and inter-sideband transition to quasi-bound states formed just beneath subband thresholds. (c) 2006 Elsevier B.V. All rights reserved.
Spin Hall effect on edge magnetization and electric conductance of a 2D semiconductor strip
(2005-09-30)
Mal'shukov, AG
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Wang, LY
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Chu, CS
;
Chao, KA
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電子物理學系
The intrinsic spin Hall effect on spin accumulation and electric conductance in a diffusive regime of a 2D electron gas has been studied for a 2D strip of a finite width. It is shown that the spin polarization near the flanks of the strip, as well as the electric current in the longitudinal direction, exhibit damped oscillations as a function of the width and strength of the Dresselhaus spin-orbit interaction. Cubic terms of this interaction are crucial for spin accumulation near the edges. As expected, no effect on the spin accumulation and electric conductance have been found in case of Rashba spin-orbit interaction.