Electrical manipulation of magnetic anisotropy in a Fe$_{81}$Ga$_{19}$/PMN-PZT magnetoelectric multiferroic composite

TL;DR

This study demonstrates efficient electrical control of magnetic anisotropy in FeGa/PMN-PZT multiferroic composites, achieving high converse magnetoelectric coefficients and significant magnetic anisotropy rotation at room temperature.

Contribution

It reports the highest known converse magnetoelectric coefficient in FeGa/PMN-PZT composites and reveals angular dependence and thermal strain effects on magnetic properties.

Findings

High converse magnetoelectric coefficient (~2.7×10^{-6} s·m^{-1}) at room temperature.

Almost 90° rotation of magnetic anisotropy axis under electric field.

Thermal strain influences magnetic coercivity differently depending on substrate.

Abstract

Magnetoelectric composites are an important class of multiferroic materials that pave the way towards a new generation of multifunctional devices directly integrable in data storage technology and spintronics. This study focuses on strain-mediated electrical manipulation of magnetization in an extrinsic multiferroic. The composite includes 5 nm or 60 nm Fe$_{81}$Ga$_{19}$ thin films coupled to a piezoelectric (011)-PMN-PZT. The magnetization reversal study reveals a converse magnetoelectric coefficient $\alpha_\mathrm{CME,max} \approx 2.7 \times {10^{-6}}$ s.m$^{-1}$ at room temperature. This reported value of $\alpha_\mathrm{CME}$ is among the highest so far compared to previous reports of single-phase multiferroics as well as composites. An angular dependency of $\alpha_\mathrm{CME}$ is also shown for the first time, arising from the intrinsic magnetic anisotropy of FeGa. The highly efficient magnetoelectric composite FeGa/PMN-PZT demonstrates drastic modifications of the in-plane magnetic anisotropy, with an almost 90$^{\circ}$ rotation of the preferential anisotropy axis in the thinner films under an electric field E = 10.8 kV.cm$^{-1}$. Also, the influence of thermal strain on the bilayer's magnetic coercivity is compared to that of a reference bilayer FeGa/Glass at cryogenic temperatures. A different evolution is observed as a function of temperature, revealing a substrate thermo-mechanical influence which has not yet been reported in FeGa thin films coupled to a piezoelectric material.