Enhancing Converse Magnetoelectric Coupling Through Strain Engineering in Artificial Multiferroic Heterostructures

Magnetoelectric materials present a unique opportunity for electric field-controlled magnetism. Even though strain-mediated multiferroic heterostructures have shown unprecedented increase in magnetoelectric coupling compared to single-phase materials, further improvements must be made before ultra-low power memory, logic, magnetic sensors, and wide spectrum antennas can be realized. This work presents how magnetoelectric coupling can be enhanced by simultaneously exploiting multiple strain engineering approaches in heterostructures composed of Fe_0.5Co_0.5/Ag multilayers on (011) Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ piezoelectric crystals. When grown and measured under strain, these heterostructures exhibit an effective converse magnetoelectric coefficient in the order of 10^-5 s m^-1: the highest directly measured, non-resonant value to-date. This response occurred at room temperature and at low electric fields (<2 kV cm^-1). This large effect is enabled by magnetization reorientation caused by changing the magnetic anisotropy with strain from the substrate and the use of multilayered magnetic materials to minimize the internal stress from deposition. Additionally, the coercive field dependence of the magnetoelectric response under strain suggests contributions from domain-mediated magnetization switching modified by voltage-induced magnetoelastic anisotropy. This work highlights how multicomponent strain engineering enables enhanced magnetoelectric coupling in heterostructures and provides an approach to realize energy-efficient magnetoelectric applications.