Intrinsic spin Hall effect in the presence of disordered magnetic impurities

Tineke van den Berg

Thursday, 20 September 2012, 14:00
Matfys library

In a two dimensional electron gas with spin-orbit coupling, the application of a (longitudinal) electric current gives rise to a transverse spin current. This phenomenon is called intrinsic spin Hall effect and for finite systems it results in accumulation of spin-polarised electrons on the sample's edges. The intrinsic spin Hall is not robust to (non-magnetic) disorder, but in the presence of magnetic impurities, that break time reversal symmetry, the effect is restored. The first quantum corrections (Cooperon) give a positive contribution to the spin Hall conductivity. At a critical disorder strength a localization transition takes place, and the local density of states shows an accumulation of electron states around the impurities. Strong antiferromagnetic correlations between the impurity- and electron-spins develop. Remarkably, in the strong disorder regime the spin Hall conductivity increases significantly.