Large angle precession of magnetization maintained by a microwave voltage

TL;DR

This paper analyzes how microwave voltage induces large angle magnetization precession via voltage-controlled magnetic anisotropy, providing insights for energy-efficient spintronics device development.

Contribution

It derives effective equations of motion for magnetization under microwave-induced anisotropy, clarifies synchronization mechanisms, and identifies conditions for stable precession.

Findings

Synchronization depends on frequency detuning and anisotropy amplitude.

Conditions for stable large angle precession are established.

Results support development of VCMA-based spintronic devices.

Abstract

Effects of a microwave voltage on magnetization precession are analyzed based on a macrospin model. The microwave voltage induces the oscillating anisotropy field through the voltage controlled magnetic anisotropy (VCMA) effect, and then stimulates the magnetization. The large angle precession is maintained if the magnetization synchronizes with the microwave voltage. The effective equations of motion of the magnetization with an oscillating anisotropy field are derived, and the mechanism of the synchronization is clarified by analyzing the derived equations of motion. The conditions of the angular frequency detuning and the amplitude of the oscillating anisotropy field for synchronization are obtained. The results are useful for development of the VCMA-based energy-efficient spintronics devices using magnetization precession such as a VCMA-based magnetoresistive random access memory and a nano-scale microwave magnetic field generator.