Transparent Ferromagnetic Films Coexisting with Ferroelectricity of the BiFeO3-PbTiO3 System Fabricated by Reactive RF-Sputtering

Reactive rf-sputtered films of solid solution compounds with (BiFeO3)1-x(PbTiO3)x(x = 0 to 1), were examined in an attempt to fabricate transparent ferromagnetic materials which are also ferroelectric above room temperature. The targets were mixed powders of Bi2O3, α-Fe2O3, PbTiO3and PbO, in which the first two components were used to synthesize BiFeO3by 1:1 mixing in mol.%, and PbO was added by 5 mol.% with respect to PbTiO3to compensate for the evaporation loss of lead during sputtering. As-grown samples deposited at about 400°C are amorphous but have noticeably large saturation magnetization of 4πMs = 210 G and saturation dielectric polarization of Ps = 0.092 μC/cm2at room temperature. The samples are turned polycrystalline by post-heat treatment at 700°C for 2 hours in air and 43film is 3.0 at λ = 700 nm.