Stable microwave-assisted magnetization switching for nanoscale exchange-coupled composite grain

Abstract

Magnetization mechanisms of nanoscale magnetic grains greatly differ from well-known magnetization mechanisms of micrometer- or millimeter-sized magnetic grains or particles. Magnetization switching mechanisms of nanoscale exchange-coupled composite (ECC) grain in a microwave field was studied using micromagnetic simulation. Magnetization switching involving a strongly damped or precessional oscillation was studied using various strengths of external direct current and microwave fields. These studies imply that the switching behavior of microwave-assisted magnetization switching of the ECC grain can be divided into two groups: stable and unstable regions, similar to the case of the Stoner-Wahlfarth grain. A significant reduction in the switching field was observed in the ECC grain when the magnetization switching involved precessional oscillations similar to the case of the Stoner-Wohlfarth grain. This switching behavior is preferred for the practical applications of microwave-assisted magnetization switching.

Physical principles of microwave assisted magnetic recording

“…Optimizing the STO design by maximizing the gradients and effective field given by Eqs. (10) and (11) yields a more potent system than the simple ones considered in this work.…”

“…It should be noted that alteration of any of these parameters does not change conclusions of this manuscript; for a more detailed recording modeling we refer the reader to specialized publications. 10 thickness is taken as 15 nm, with 5 nm spacing between the pole and the media surface. The pole material has saturation magnetization of 4pM s ¼ 2:4T.…”