Magneto-optical imaging of voltage-controlled magnetization reorientation

TL;DR

This study evaluates the macrospin model's effectiveness in describing voltage-induced magnetization reorientation in nickel thin films, demonstrating its validity on large scales except near coercive fields where domain effects dominate.

Contribution

It provides experimental validation of the macrospin model's applicability to voltage-controlled magnetization reorientation, highlighting its limitations around coercive fields due to domain effects.

Findings

Macrospin model accurately predicts magnetoresistance under voltage control.

Limitations of the macrospin model near coercive fields due to domain effects.

Voltage control effectively reorients magnetization on large length scales.

Abstract

We study the validity and limitations of a macrospin model to describe the voltage-controlled manipulation of ferromagnetic magnetization in nickel thin film/piezoelectric actuator hybrid structures. To this end, we correlate simultaneously measured spatially resolved magneto-optical Kerr effect imaging and integral magnetotransport measurements at room temperature. Our results show that a macrospin approach is adequate to model the magnetoresistance as a function of the voltage applied to the hybrid, except for a narrow region around the coercive field - where the magnetization reorientation evolves via domain effects. Thus, on length scales much larger than the typical magnetic domain size, the voltage control of magnetization is well reproduced by a simple Stoner-Wohlfarth type macrospin model.