Numerical simulations of a ballistic spin interferometer with Rashba spin-orbital interaction

Abstract

We numerically investigate the transport behavior of a quasi-one-dimensional (1D) square loop device containing the Rashba spin-orbital interaction in the presence of a magnetic flux. The conductance versus the magnetic field shows the Al'tshuler-Aronov-Spivak (AAS) and Aharonov-Bohm (AB) oscillations. We focus on the oscillatory amplitudes, and find that both of them are strongly dependent on the spin precession angle (i.e., the strength of the spin-orbit interaction) and exhibit no periodic oscillations, in good agreement with a recent experiment by Koga et al. [cond-mat/0504743 (unpublished)]. However, our numerical results for the ideal 1D square loop device for the node positions of the amplitudes of the AB and AAS oscillations are found to show some discrepancies with the results for quasi-1D square loops with a finite width. In the presence of disorder and taking the disorder ensemble average, the AB oscillation in the conductance disappears, while the time-reversal symmetric AAS oscillation still remains. Furthermore, the node positions of the AAS oscillatory amplitude remain the same.