Unequal activation volumes of well-motion and nucleation process in Co/Pt multilayers

Abstract

Magnetic field dependence of magnetization reversal in ColPt multilayers was qmmtitatively investigated. Serial

samples of ColPt multilayers were prepared by dc-magnetron sputtering under various Ar pressures. Magnetization

reversal was monitored by magnetization viscosity measurement and direct domain observation using a

magneto-optical microscope system, and the wall-motion speed V and the nucIeation rate R were determined

using a domain reversal model based on time-resolved domain reversal pattems. Both V and R were found to be

exponentially dependent on the applied reversing field. From the exponential dependencies, the activation volumes

for wall motion and nucIeation could be determined, based on a thermally activated relaxation model, and

the wall-motion activation volume was found to be slightIy larger than the nucIeation activation volume.