Surface-induced reduction of the switching field in nanomagnets

Abstract

Magnetization reversal in a many-spin nanomagnet subjected to an rf magnetic field, on top of a DC magnetic field, is studied by numerically solving the system of coupled (damped) Landau-Lifshitz equations. It is demonstrated that spin-misalignment induced by surface anisotropy favors switching with a DC magnetic field weaker than the Stoner-Wohlfarth switching field, for optimal intensities and frequencies of the rf field.