Sign and magnitude of spin Hall effect in CuBi alloys

CuBi合金におけるスピンホール効果の符号と振幅

Gu, B.

Gu, B.

We show that the confusing sign problem of SHA in CuBi alloys between the experiment and the established theories was due to the inconsistent definitions of SHA. Once the confusion of definitions is removed there is no contradiction to a skew scattering mechanism, and thus we restore the possibility of properly microscopic understanding of the effects. We find that the SHA can be dramatically enhanced by Bi impurities close to the Cu surface. The mechanisms are two-fold. One is that the localized impurity state on surface has a decreased hybridization and combined with Coulomb correlation effect, this leads to an enhanced SHA. The other comes from the low-dimensional state of conduction electrons on surface, which results in a further enhancement of skew scattering by impurities. Our results may explain the giant SHA experimentally observed in CuBi alloys.