Determination of the energy barrier and spin torque efficiency based on telegraph noise

Abstract

The spin torque (ST) efficiency and energy barrier of domain wall (DW) depinning are investigated by analyzing the telegraph noise in nanostructured ferromagnetic Pt/Co/Pt films. The telegraph noise is generated by applying both a magnetic field and an electric current, whose forces on the DW oppose each other. Cumulating the DW depinning probability experimentally revealed that the DW depinning was governed by a single energy barrier, whose height was estimated to be about 1.0 x 10(-19) J. The ST efficiency at the pinning site is estimated to be -4.6 x 10(-14) T center dot m(2)/A. The present analysis technique provides an alternative way to determine the ST efficiency in the short-current-pulse-driven DW motion at a single energy barrier.