Current noise generated by spin imbalance in presence of spin relaxation

Abstract

We calculate current (shot) noise in a metallic diffusive conductor generated by spin imbalance in the absence of a net electric current. This situation is modeled in an idealized three-terminal setup with two biased ferromagnetic leads (F-leads) and one normal lead (N-lead). Parallel magnetization of the F-leads gives rise to spin-imbalance and finite shot noise at the N-lead. Finite spin relaxation results in an increase in the shot noise, which depends on the ratio of the length of the conductor (L) and the spin relaxation length (l_s). For L >> l_s the shot noise increases by a factor of two and coincides with the case of the antiparallel magnetization of the F-leads.