Magnetism control of FeGa/BTO thin films by Electric-field

Summary form only given. Controlling the magnetism by means of electric fields is a key issue for the future development of low-power spintronics. Usually, electric-field can control the magnetic materials by oxide-gate structures. But this approach has a low regulatory capacity drawback than a way of controlled on BaTiO₃ (BTO) by the magnetoelectricity coupling, such as the experiments of FeRh/BaTiO₃, BaTiO₃/La_0.67Sr_0.33MnO and Pb(Mg_1/3Nb_2/3)_0.7Ti_0.3O₃/Co₄₀Fe₄₀B₂₀. FeGa alloy and BTO oxide are laminated to form heterostructure for high magnetoelectricity. Ga could contribute to preferential magnetization along the <;100> direction in FeGa alloys and thus create anisotropy in the material, which is higher than the pure Fe. Here we report the magnetic control of FeGa thin films on BaTiO₃ substrate by electric field. 20 nm thick FeGa films were grown by sputtering onto BaTiO₃ single crystal substrate . BTO will have an influence to the FeGa when applying a voltage between the upper and lower surfaces . The magneto-optic Kerr effect (MOKE) magnetometer was utilized to detect the magnetism variations of the FeGa thin film . We firstly examined the hysteresis loops of FeGa films at room temperature . The square-shaped magnetic hysteresis loop was observed with applied magnetic field H between -150 Oe to +150 Oe in [100] orientation, where the saturation field of FeGa thin film is 45Oe . We also measured another axis loop with H perpendicular to the axis [100] (the Ω=90°). We then studied the changes of magnetic properties in FeGa/BTO thin films by applying voltage to the BTO substrate. With increasing the applied voltage, the coercivity of the [100] axis was gradually enlarged and the saturation field of another axis perpendicular to the axis [100] also increased, indicating that axis- become more hard . The voltage added to BTO substrate controlled the magnetism change of the FeGa thin film . Our results suggest that the electric-field through BTO substrate can be used to control the spintronics devices effectively.