Giant Edge Spin Accumulation in a Symmetric Quantum Well with Two Subbands

DIPC Seminars

Speaker

Alexander Khaetskii (Dept. of Physics, University at Buffalo, USA)

When

2017/01/19
13:00

Place

Donostia International Physics Center

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We have studied the edge spin accumulation due to electric current in a high mobility two-dimensional electron gas formed in a symmetric well with two subbands. This study is strongly motivated by the recent experiment of Hernandez et al. [Phys. Rev. B 88, 161305(R) (2013)] who demonstrated the spin accumulation near the edges of a bilayer symmetric GaAs structure in contrast to no effect in a single-layer configuration. The intrinsic mechanism of the spin-orbit interaction we consider arises from the coupling between two-subband states of opposite parities. We obtain a parametrically large magnitude of the edge spin density for a two-subband well as compared to the usual single-subband structure. We show that the presence of a gap in the system, i.e., the energy separation between the two subband bottoms, changes drastically the picture of the edge spin accumulation. Thus one can easily proceed from the regime of weak spin accumulation to the regime of strong one by varying the Fermi energy (electron density) and/or gap value. We estimate that by changing the gap from zero up to 1-2 K only, the magnitude of the effect changes by three orders of magnitude. This opens up the possibility for the design of new spintronic devices. Moreover, our work explains many important theoretical features of the edge spin accumulation phenomenon for the intrinsic mechanism that in our opinion have not been really understood in previous studies.