Competing D’yakonov–Perel’ and Elliott–Yafet spin relaxation in germanium

In most technologically important semiconductors, the two main spin relaxation mechanisms are the D’yakonov–Perel’ (DP) and the Elliott–Yafet (EY) modes. In the former, the spin relaxation rate increases, while in the latter it decreases, with increasing carrier mobility. Accordingly, the DP mode should dominate in high-mobility samples and the EY mode in low-mobility ones. We have carried out experiments in high-mobility bulk and low-mobility nanowire samples of germanium and found that indeed the DP mode dominates in the high-mobility samples and the EY mode in the low-mobility ones. The DP relaxation time was found to be three orders of magnitude shorter than the EY relaxation time. This suggests that low-mobility samples may be preferable for some spintronic applications.