A scheme for spin transistor with extremely large on/off current ratio
  Quantum wires with periodic local Rashba spin-orbit couplings are proposed for a higher performance of spin field-effect transistor. Fano-Rashba quantum interference due to the spin-dependent modulated structure gives rise to a broad energy range of vanishingly small transmission. Tuning Rashba spin-orbit couplings can provide the on- or off-currents with extremely large on/off current ratios even in the presence of a strong disorder. 
L. Wang, K. Shen, S. Y. Cho, M. W. Wu