Time-Resolved Spin Torque Switching and Enhanced Damping in Py/Cu/Py Spin-Valve Nanopillars

摘要

We report time-resolved measurements of current-induced reversal of a freemagnetic layer in Py/Cu/Py elliptical nanopillars at temperatures T = 4.2 K to160 K. Comparison of the data to Landau-Lifshitz-Gilbert macrospin simulationsof the free layer switching yields numerical values for the spin torque and theGilbert damping parameters as functions of T. The damping is stronglyT-dependent, which we attribute to the antiferromagnetic pinning behavior of athin permalloy oxide layer around the perimeter of the free layer. Thisadventitious antiferromagnetic pinning layer can have a major impact on spintorque phenomena.