Issues pertaining to D'yakonov-Perel' spin relaxation in quantum wire   channels
  We elucidate the origin and nature of the D'yakonov-Perel' spin relaxation in a quantum wire structure, showing (analytically) that there are three necessary conditions for it to exist: (i) transport must be multi-channeled, (ii) there must be a Rashba spin orbit interaction in the wire, and (iii) there must also be a Dresselhaus spin orbit interaction. Therefore, the only effective way to completely eliminate the D'yakonov-Perel' relaxation in compound semiconductor channels with structural and bulk inversion asymmetry is to ensure strictly single channeled transport. In view of that, recent proposals in the literature that advocate using multi-channeled quantum wires for spin transistors appear ill-advised. 
S. Pramanik, S. Bandyopadhyay and M. Cahay