Giant edge spin accumulation in a symmetric quantum well with two subbands
Abstract
We have studied the edge spin accumulation due to an electric current in a high mobility twodimensional 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 (2013) 161305(R)) who demonstrated the spin accumulation near the edges of a symmetric bilayer GaAs structure in contrast to no effect in a singlelayer configuration. The intrinsic mechanism of the spinorbit (SO) 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 twosubband well as compared to the usual singlesubband structure. We show that the presence of a gap in the system, i.e., the energy separation Δ between the two subband bottoms, changes drastically the picture of the edge spin accumulation. The gap value governs the effective strength of the intersubband SO interaction which provides a controllable crossover from the regime of weak spin accumulation to the regime of the strong one by varying the Fermi energy (electron density) and/or Δ. We estimate that by changing the gap Δ from zero up to 12 K, the magnitude of the effect changes by three orders of magnitude. This opens up the possibility for the design of new spintronic devices.
 Publication:

EPL (Europhysics Letters)
 Pub Date:
 June 2017
 DOI:
 10.1209/02955075/118/57006
 arXiv:
 arXiv:1602.00026
 Bibcode:
 2017EL....11857006K
 Keywords:

 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 6 pages, 2 figures, expanded text and added Supplementary Material