Multiferroic properties of Dy modified BiFeO₃ thin films in comparison with Tb modified BiFeO₃ thin films

Coexistence of ferroelectric and ferromagnetic order parameters was observed at room temperature in Bi_0.6Dy_0.3La_0.1FeO₃ thin films grown on Pt/TiO₂/SiO₂/Si substrates using a pulsed laser deposition technique similar to that for Bi_0.6Tb_0.3La_0.1FeO₃. The coexistence of ferroelectric and magnetic domains in specific spatial area of the thin film was also confirmed by scanning probe imaging. As expected, the magnetization values obtained for Bi_0.6Dy_0.3La_0.1FeO₃ bulk and thin films were higher than those of Bi_0.6Tb_0.3La_0.1FeO₃ bulk and polycrystalline thin films because the magnetic moment of Dy is higher than that of Tb. However, preferentially oriented thin films of Bi_0.6Tb_0.3La_0.1FeO₃ exhibit much higher magnetization values. It is speculated that structural alignment caused by stress developed during deposition of these films could be responsible for enhancement in magnetization.