Study of One-Side-Flat Edge on Vortex in Submicro-Scaled Permalloy Disks

By introducing a one-side-flat edge to a submicroscaled Permalloy disk, the isotropy of the disk is broken to achieve the control on vortex nucleation and annihilation. Series one-side-flat magnetic disk arrays with different cutting percentages of disk are fabricated to observe the influence from asymmetry on the vortex configuration in submicroscaled magnetic disks. In the excised angles were varied from 15^° to 90^° in 500-nm-diameter and 40-nm-thick NiFe disk arrays, it is observed the dependences of vortex nucleation and annihilation fields on the asymmetry. Linear relations of vortex nucleation and annihilation fields to aspect ratio were found that would be useful for controlling nucleation and annihilation fields on purpose. Micromagnetism simulations for Permalloy disk array with a diameter of 500 nm and different excise dangles were executed to compare with experimental data. The relations of vortex existence field to the aspect ratio were found that could be taken into account for designing single vortex element applications. In addition to magnetic field parallel to excised flat edge, the constant perpendicular field (Hy) applied to sample could change vortex nucleation and annihilation field of Py disk array. Finally, It was found that a higher asymmetry effect could depress the unpleasantly interactions and lead to a narrow range of switching field distribution, which was an important index for designing high-density magnetic devices.