Thickness Dependences of Nucleation and Annihilation Fields of Magnetic Vortices in Submicron Supermalloy Dots

Abstract

Vortex nucleation and annihilation fields have been studied from the M–H loop of submicron-size ferromagnetic (supermalloy) circular-dot arrays. Both the nucleation and annihilation fields increase with increasing thickness for all measured diameters. For comparison, micromagnetic simulation was also carried out for a single circular dot and the same behavior was observed. Micromagnetic simulation suggested that the increase in magnetostatic energy with increasing thickness plays an essential role in the increase in the nucleation and annihilation fields.