Giant electric field controlled magnetic anisotropy in epitaxial BiFeO ₃-CoFe₂O₄ thin film heterostructures on single crystal Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O ₃ substrate

We have deposited self-assembled BiFeO₃ (BFO)-CoFe ₂O₄ (CFO) thin films on Pb(Mg_1/3Nb _2/3)_0.7Ti_0.3O₃ (PMN-PT) substrates and studied the change in magnetic anisotropy under different strain conditions induced by an applied electric field. After electric field poling, we observed (i) giant magnetization change: magnetization of original CFO phase is three times larger than that of strained one and (ii) magnetic force microscopy line profiles that exhibited significant change in the CFO magnetic domain response in accordance to magnetization-field (M-H) loops. Together, these results demonstrate good control of the magnetic properties of CFO via an electric field induced strain.