Abstract
Strain-mediated ferromagnetic/ferroelectric (FE) heterostructures have played an important role in multiferroic materials to investigate the electric-field control of magnetism in the past decade, due to their excellent performances, such as room-temperature operation and large magnetoelectric (ME) coupling effect. Because of the different FE-switching-originated strain behaviors and varied interfacial coupling effect, both loop-like (nonvolatile) and butterfly-like (volatile) converse ME effects have been reported. Here, we investigate the electric-field control of magnetism in a multiferroic heterostructure composed of a polycrystalline Fe thin film and a Pb(Mg1/3Nb2/3)(0.7)Ti0.3O3 single crystal, and the experimental results exhibit complex behaviors, suggesting the coexistence of volatile and nonvolatile converse ME effects. By separating the symmetrical and antisymmetrical parts of the electrical modulation of magnetization, we distinguished the loop-like hysteresis and butterfly-like magnetization changes tuned by electric fields, corresponding to the strain effects related to the FE 109 degrees switching and 71/180 degrees switching, respectively. Further magnetic-field dependent as well as angular-dependent investigation of the converse ME effect confirmed the strain-mediated magnetism involving competition among the Zeeman energy, magnetocrystalline anisotropy energy, and strain-generated magnetoelastic energy. This study is helpful for understanding the electric-field control of magnetism in multiferroic heterostructures as well as its relevant applications.