Intrinsic spin Hall effect in the presence of disordered magnetic
impurities
Tineke van den Berg
Thursday, 20 September 2012, 14:00
Matfys library
Abstract:
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.