Spin dynamics of magnonic crystals and ferromagnetic nanorings

Abstract

The overall objective of this PhD research study is to investigate the magnonic band structures of SWs in one- and two-dimensional bi-component MCs using both experimental Brillouin light scattering and the micromagnetic simulations. The observed bandgaps have been demonstrated to be tunable by varying the geometrical and material parameters, as well as the applied magnetic field. The entire band structure is found to be blue shifted in frequency while the bandgap widths become narrower with increasing applied field strength. Our findings reveal the existence of magnonic bandgaps in the MCs studied, and are expected to stimulate further development of the theory and applications of magnonics. The field-orientation dependence of the magnetization reversal and SW modes in elongated nanorings has also been investigated. Our Brillouin data reveal a splitting of each SW mode into two modes, corresponding to the transition from the onion to the vortex state, when the field was applied along the magnetization easy axis of the nanorings.