Electrical Manipulation of Magnetic Anisotropy in a Fe81Ga19/Pb(Mg1/3Nb2/3)O3-Pb(ZrxTi1−x)O3 Magnetoelectric Multiferroic Composite

Magnetoelectric composites are an important class of multiferroic materials that are paving the way towards a new generation of multifunctional devices directly integrable into data-storage technology and spintronics. This study focuses on strain-mediated electrical manipulation of magnetization in an extrinsic multiferroic. The composite used includes 5- or 60-nm ${\mathrm{Fe}}_{81}{\mathrm{Ga}}_{19}$ thin films coupled to a piezoelectric (011) $\mathrm{Pb}({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}){\mathrm{O}}_{3}$-$\mathrm{Pb}({\mathrm{Zr}}_{x}{\mathrm{Ti}}_{1\ensuremath{-}x}){\mathrm{O}}_{3}$ (PMN-PZT) material. A magnetization-reversal study reveals a converse magnetoelectric coefficient ${\ensuremath{\alpha}}_{\mathrm{CME},max}\ensuremath{\approx}2.7\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\phantom{\rule{0.2em}{0ex}}\mathrm{s}\phantom{\rule{0.1em}{0ex}}{\mathrm{m}}^{\ensuremath{-}1}$ at room temperature. This reported value of ${\ensuremath{\alpha}}_{\mathrm{CME}}$ is among the highest so far, compared with previous reports on single-phase multiferroics and on composites. An angular dependence of ${\ensuremath{\alpha}}_{\mathrm{CME}}$ is also shown, arising from the intrinsic magnetic anisotropy of $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Ga}$. The highly efficient magnetoelectric composite $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Ga}$/PMN-PZT demonstrates drastic modifications of the in-plane magnetic anisotropy, with an almost ${90}^{\ensuremath{\circ}}$ rotation of the preferential anisotropy axis in thinner films under an electric field $E=10.8\phantom{\rule{0.2em}{0ex}}\mathrm{kV}\phantom{\rule{0.1em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$. Also, the influence of thermal strain on the bilayer's magnetic coercivity is compared with that for a reference $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Ga}$/glass bilayer at cryogenic temperatures. A different evolution is observed as a function of temperature, revealing a thermomechanical influence of the substrate which has not yet been reported in $\mathrm{Fe}\text{\ensuremath{-}}\mathrm{Ga}$ thin films coupled to a piezoelectric material.