Rotational Symmetry Breaking Enhanced Frequency Comb of NiFe Vortex in a Square Disk

Abstract

This work explores the frequency comb of magnetic vortex in a square disk and a circular disk created by an out-of-plane and in-plane oscillating field using micromagnetic modeling. The broadest frequency comb ever observed in a magnetic system is displayed. When driven by an out-of-plane field, the robustness of the frequency comb of a vortex in a square disk is significantly enhanced due to a reduction in rotational symmetry when compared to a vortex in a circular disk. In addition, comb lines increase as driven amplitude increases, and frequency spacing could be adjusted in the square disk, so facilitating its application. In a situation where the vortex is driven by in-plane field, the square disk exhibits a significantly neater frequency comb than the circular disk. The conclusion is that magnetic vortex in a square disk is better suited for frequency comb applications.