Electrical and thermal control of magnetic coercive field in ferromagnetic/ferroelectric heterostructures

We report the growth of ferromagnetic epitaxial CoFe2O4 (CFO) thin films on 011-oriented tetragonal-structured 0.62Pb(Mg,Nb)O3-0.38PbTiO3 single crystal substrates. In the substrates, electric field-induced polarization reorientation resulted in maximum strains of -1.3% and 0.64% along in-plane 100 and along in-plane 01̄1, respectively. As a consequence, in the CFO films, irreversible magnetic coercive field changes of 580, -510, and -220 Oe were observed along in-plane 100 and 01̄1 and out-of-plane 011, respectively, after electric field poling. After annealing at 470 K, the substrate depoled, and both the magnetic coercive fields and the remnant magnetizations along the three directions recovered their original values.