Electric-field-induced strain-mediated magnetoelectric effect in CoFeB-MgO magnetic tunnel junctions

Abstract: Magnetoelectric coupling between magnetic and electric dipoles is one of the cornerstones of modern physics towards developing the most energy-efficient magnetic data storage. Conventionally, magnetoelectric coupling is achieved in single-phase multiferroics or in magnetoelectric composite nanostructures consisting of ferromagnetic and ferroelectric/piezoelectric materials. Here, we demonstrate an electric-field-induced strain-mediated magnetoelectric effect in ultrathin CoFeB/MgO magnetic tunnel junction employing non-piezoelectric material, which is a vitally important structure for spintronic devices, by using dynamical magnetoelectric and piezoresponse force microscopy measurement techniques. We show that the applied electric-field induces strain in a few atomic layers of dielectric MgO which is transferred to magnetostrictive CoFeB layer, resulting in a magnetoelectric effect of magnitude up to 80.8 V cm-1 Oe-1 under -0.5 V. The demonstrated strain-mediated magnetoelectric effect with an electric field in magnetic tunnel junctions is a significant step towards exploring magnetoelectrically controlled spintronic devices for low-power and high density magnetic data storage applications.