Structural, electrical, and magnetic properties of multiferroic Bi1-xLaxFe1-yCoyO3 thin films

Bi1-xLaxFe1-yCoyO3 (x=0, 0.1; y=0, 0.05, 0.1) polycrystalline thin films were fabricated on Pt/Ti/SiO2/ Si(III) substrates via chemical solution deposition method. X-ray diffraction analysis revealed a phase transition in La-Co codoped BiFeO3 (BFO) thin films. Saturated ferroelectric hysteresis characteristics in La-Co codoped BFO thin films were observed, and the conduction behavior of Bi1-xLaxFe1-yCoyO3 thin films investigated to understand the leakage mechanisms. In the low applied field, the conduction mechanism of Bi1-xLaxFe1-yCoyO3 thin films was found to be dominantly Ohmic. In the high applied field, the conduction mechanisms of pure and La doped BFO thin films were found to be trap-filled-limited and Poole-Frenkel emission, and that of Co doped and La-Co codoped BFO thin films Schottky emission. The dielectric constant of Bi0.9La0.1Fe0.9Co0.1O3 thin film, in the frequency range of 1 to 2000 kHz, was nearly two times higher than that of pure BFO thin film while the dielectric loss tan delta was small at values below 0.07. It was found that saturation magnetization in BFO thin films could be enhanced by La or Co doping, and obviously by La-Co codoping too. (c) 2010 American Institute of Physics. [doi:10.1063/1.3437232]