CMSP Seminar @ICTP Stasi Seminar Room Monday 25 July at 11.00 a.m. - Alexander KHAETSKII

[Condensed Matter Section]

Condensed Matter and Statistical Physics Seminar
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Monday 25 July at 11.00 a.m.
Luigi Stasi Seminar Room, first floor, Leonardo building

Alexander KHAETSKII(Dept. of Physics, University at Buffalo, SUNY, 
Buffalo, NY, USA)

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

Abstract:

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.