Influence of asymmetric disks on control over the existence of vortex in submicrometer-scaled Permalloy disks

Abstract

The influence of the degree of asymmetry of a Py disk in a vortex configuration by changing an excised angle is studied in this paper. Samples of 40 nm thick NiFe disk arrays, with excised angles varying from 15° to 90° and diameters of 800, 500, and 300 nm, were investigated to observe the dependence of vortex nucleation and annihilation fields on the asymmetry and dimensions. Linear relations of vortex nucleation and annihilation fields to aspect ratio were found, and are useful mainly for controlling the nucleation and annihilation fields. Relationships between the vortex existence field and the aspect ratio, a thickness and diameter were found, and these should be taken into account when designing single vortex element applications.