  We consider the general Landau-Lifshitz-Gilbert (LLG) dynamical theory
underlying the magnetization switching rates of a thin film uniaxial magnet
subject to spin-torque effects and thermal fluctuations (thermal noise). After
discussing the various dynamical regimes governing the switching phenomena, we
present analytical results for the mean switching time behavior. Our approach,
based on explicitly solving the first passage time problem, allows for a
straightforward analysis of the thermally assisted, low spin-torque, switching
asymptotics of thin film magnets. To verify our theory, we have developed an
efficient GPU-based micromagnetic code to simulate the stochastic LLG dynamics
out to millisecond timescales. We explore the effects of geometrical tilts
between the spin-current and uniaxial anisotropy axes on the thermally assisted
dynamics. We find that even in the absence of axial symmetry, the switching
times can be functionally described in a form virtually identical to the
collinear case. We further verify that asymptotic behavior is reached fairly
slowly, thus quantifying the role of thermal noise in the crossover regime
linking deterministic to thermally assisted magnetization reversal.

Mesoscale and Nanoscale Physics;Materials Science