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Title: Spin current and its superfluid

Speaker: X.C. Xie International Center for Quantum Materials and School of Physics, Peking University

Location: Room 111, Physics Building

Time: 3:00pm, 17-10-2012, Wednesday

Abstract:

In this talk, I will review some basic physical properties of spin current. Furthermore, I will present our recent theoretical study of the possible existence of a spin superfluid (SSF) in a ferromagnetic graphene system. The spin superfluid, a counterpart to the charge superconductor, in which a spin-polarized electron-hole excitons play the roles of the `Cooper' pairs. We present a BCS-type theory for the SSF. With the ``London-type equations" of the spin-super-current density, we show the existence of an electric ``Meissner effect" against a spatial varying electric field. We further study a SSF/normal conductor/SSF junction and predict a spin-current Josephson effect.