  Motivated by recent experimental studies of thin-film devices containing a
single ferromagnetic layer, we develop a quantum kinetic theory of
current-induced magnetic torques in Rashba-model ferromagnets. We find that
current-induced spin-densities that are responsible for the switching behavior
are due most essentially to spin-dependent quasiparticle lifetimes and derive
analytic expressions for relevant limits of a simple model. Quantitative model
parameter estimates suggest that spin-orbit coupling in the adjacent metal
normal magnetic layer plays an essential role in the strength of the switching
effect.
