"Nonuniform switching of the perpendicular magnetization in a spin-torque-driven magnetic nanopillar"

David P. Bernstein: Björn Bräuer, Roopali Kukreja, Joachim Stöhr, Thomas Hauet, Julien Cucchiara, Stéphane Mangin, Jordan A. Katine, Tolek Tyliszczak, Kang W. Chou, Yves Acremann; Phys. Rev. B , 05/10/11.

Additional Authors: Björn Bräuer, Roopali Kukreja, Joachim Stöhr, Thomas Hauet, Julien Cucchiara, Stéphane Mangin, Jordan A. Katine, Tolek Tyliszczak, Kang W. Chou, Yves Acremann

Abstract:

Time-resolved scanning transmission x-ray microscopy measurements were performed to study the current-induced magnetization switching mechanism in nanopillars exhibiting strong perpendicular magnetic anisotropy. This technique provides both short-time (70 ps) and high-spatial (25 nm) resolutions. Direct imaging of the magnetization demonstrates that, after an incubation time of ~1.3 ns, a 100×300 nm2 ellipsoidal device switches in ~1 ns via a central domain nucleation and opposite propagation of two domain walls toward the edges. High domain-wall velocities on the order of 100 m/s are measured. Micromagnetic simulations are shown to be in good agreement with experimental results and provide insight into magnetization dynamics during the incubation and reversal periods.