Multiferroic properties of sputtered BiFeO3 thin films

A cosputtering method was used to deposit BiFeO3 thin films on Pt∕Ti∕SiO2∕Si substrates. It was confirmed as a polycrystalline film with a tetragonal crystal structure in the annealed state. Both Fe2+ and Fe3+ ions were found to coexist in the film. The leakage current density is as low as 10−3A∕cm2 at 120kV∕cm. This sputtered film shows multiferroic properties exhibiting a saturated ferroelectric loop with a large remnant polarization of 37μC∕cm2 and a saturated ferromagnetic loop with saturation magnetization of 21emu∕cm3 at room temperature.