Giant Magnetoelectric Effect and Interactive Control of Magnetic Anisotropy Driven by a Ferroelectric Phase Transition in Ferromagnetic-Piezoelectric Heterostructure

Magnetoelectric materials and, to a larger extent, multiferroic heterostructures offer a novel route for electric field control of magnetism. We explored the induced magnetic anisotropy of an FeCo/Ag multilayer thin film deposited on the surface of 001 poled (Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ PIN-PMN-PT single crystal as it is electrically driven through a ferroelectric-ferroelectric phase transition. In PIN-PMN-PT an effective giant piezoelectric coefficient >10,000 pm/V occurs during the phase transition providing strain >0.25% along a principle strain direction. This effect translates into anisotropic strain to the magnetoelastic thin film inducing a giant magnetoelastic effect driven by the induced magnetic anisotropy along the principle strain direction. We measured an effective converse magnetoelectric coefficient ~1.4 x 10^-5 s/m when driven through the phase transition which was more than double the values obtained in the linear piezoelectric rhombohedral phase. The controllable and repeatable nature of the phase transition allows an interactive driving of the induced magnetization making the phenomenon attractive for application in spintronic devices.