Electric-field control of magnetic anisotropy in Fe₈₁Ga₁₉/BaTiO₃ heterostructure films

We investigate the control of magnetism with an electric field in Fe₈₁Ga₁₉(FeGa)/BaTiO₃(BTO) heterostructure films. The as-prepared FeGa/BTO samples present a uniaxial magnetic anisotropy, which is ascribed to be induced by the spontaneous ferroelectric polarization of the BTO substrates. With the electric field applied on the BTO substrates increasing from 0 to 6 kV/cm, the coercivity of FeGa films measured along the BTO[110] direction increases from 28 to 41 Oe, while the squareness of the hysteresis loop decreases from 0.99 to 0.31, which indicates that the easy and hard axes of FeGa films are swapped. The ferroelectric domains of BTO substrates and the magnetic domains of FeGa films exhibit the same dependence on the applied electric fields, manifesting the strong magnetoelectric coupling between the ferroelectricity of BTO substrates and the magnetism of FeGa films.