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

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

Place: Donostia International Physics Center

Date: Thursday, 19 January 2017, 12:00

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.

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