Nonlinear Spin Polarized Transport through a Ferromagnetic-Nonmagnetic-Ferromagnetic Junction

Abstract

We present a theoretical analysis of the nonlinear bias and temperature dependence of current-voltage characteristics of a spin-valve device which is formed by connecting a nonmagnetic system to two ferromagnetic electrodes whose magnetic moments orient at an angle θ with respect to each other. The theory is based on nonequilibrium Green's function approach and focused on current perpendicular to plane geometry. Coulomb interaction has been taken into account explicitly at the Hartree level. We derive a formula in closed form for current flowing through the device in general terms of bias and temperature. In the wideband limit we report exact results for the tunneling magnetoresistance (TMR) junction nonlinear I-V curve as a function of θ. We also report the conductance slope at zero bias as a function of temperature for which experimental results reported an anomalous behavior.