Thermal Stability in Uniaxial Nanomagnets Driven by Spin-Polarized Currents

Nanomagnets with uniaxial symmetry driven by spin-polarized currents are considered, in which anisotropy, applied field, and spin polarization are all aligned along the symmetry axis. Thermal fluctuations are taken into account by adding a Gaussian white noise stochastic term to the equation for the deterministic dynamics. The corresponding Fokker-Planck equation is derived. It is shown that the deterministic dynamics and the thermal relaxation are both governed by an effective potential including the effect of current injection