Spin Josephson effect in spintronic nanostructures

Abstract

The problem of spin current across a ferromagnetic/normal metal/ferromagnetic junction is formulated. It is shown that the spin current is controlled by the phase difference across the junction. Under zero bias, J A system which is of particular interest in fundamental physics and device applications is a structure where the left and right ferromagnetic leads are separated by a nonmagnetic barrier, or an FNF junction. Since a polarised spin state has a well-defined amplitude and phase, one can immediately draw straightforward analogies between the relevant quantities in an FNF junction for spin transport and a superconducting/insulator/superconductor (SIS) junction for charge transport [8]. In a recent work [9] such direct analogies were used to derive a spin current in the form similar to the super-current across an SIS junction, J