Intrinsic spin Hall effect in silicene: transition from spin Hall to normal insulator

An intrinsic contribution to the spin Hall effect in two-dimensional silicene is considered theoretically within the linear response theory and Green's function formalism. When an external voltage normal to the silicene plane is applied, the spin Hall conductivity is shown to reveal a transition from the spin Hall insulator phase at low bias to the conventional insulator phase at higher voltages. This transition resembles the recently reported phase transition in bilayer graphene. The spinorbit interaction responsible for this transition in silicene is much stronger than in graphene, which should make the transition observable experimentally. (c) 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim