Proof-of-Concept for Selective Magnetization Switching for Microfabricated Exchange-Spring Magnets by Spin Wave Excitation

Abstract

This paper presents a proof-of-concept for selective magnetization switching in microfabricated elements with L1₀-FePt/Ni₈₁Fe₁₉ (permalloy; Py) exchange-coupled bilayers, known as exchange-spring magnets, by exciting spin wave dynamics. Although the resonance frequency of the perpendicular standing spin wave mode definitely can be tuned by varying the Py layer thickness or the aspect ratio of the element, considering the requirements of selective magnetization switching, it is found that the frequency tuning by varying the aspect ratio is suitable. The spin wave-assisted magnetization switching (SWAS) experiments for the different aspect ratios reveal the condition for the switching field reduction for each aspect ratio. Thanks to the different resonance frequencies between the different aspect ratios, the selective nature of SWAS method is experimentally demonstrated. The findings involve the contribution of higher-order spin wave dynamics, and emphasize the significance of adjusting the aspect ratio of elements to realize selective magnetization switching, offering potential applications in multilevel recording media.