A research team led by Professor J. Stohr (SLAC National Accelerator Laboratory, Stanford, USA) has recently performed time-resolved scanning transmission X-ray microscopy measurements to study the current-induced magnetization switching mechanism in nanopillars exhibiting strong perpendicular magnetic anisotropy. Because of both the short-time (70 ps) and high-spatial (25 nm) resolutions of this imaging technique, the detailed mechanism has become clear as follows; after an incubation time of ~1.3 ns, a 100×300nm2 ellipsoidal device switches in ~1 ns via a central domain nucleation and opposite propagation of two domain walls toward the edges. For further understanding, micromagnetic simulations were done and shown as being in good agreement with experiments. For more information, see the paper, "Nonuniform switching of the perpendicular magnetization in a spin-torque-driven magnetic nanopillar", D. P. Bernstein et al., Phys. Rev. B83, 180410(R) (2011).
