Peter Boross, Balazs Dora, Annamaria Kiss, Ferenc Simon
We present a unified treatment of the Elliott-Yafet (EY) and the D'yakonov-Perel' (DP) spin-relaxation mechanisms using the Mori-Kawasaki formula, which gives the spin-relaxation rate to lowest order in the spin-orbit coupling (SOC) but to infinite order in the quasi-particle scattering rate, Gamma. We consider a four-state Hamiltonian of the conduction and a nearby (valence) band with spin degeneracy, including SOC between adjacent bands (inter-SOC) and within the same band (intra-SOC). We find in agreement with the expectations that intra-SOC yields the DP- whereas the inter-SOC the EY-like result. However, we identify parameter domains of Gamma and the band structure where a crossover occurs between the two types of spin-relaxation mechanisms. The result ultimately connects the EY and the DP spin-relaxation mechanisms into a unified description and it leads to a better understanding of spin-relaxation in strongly correlated systems and where band degeneracy plays a role such as e.g. in graphene.
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http://arxiv.org/abs/1211.0826
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