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

Bi 1 − x La x Fe 1 − y Co y O 3 (x=0, 0.1; y=0, 0.05, 0.1) polycrystalline thin films were fabricated on Pt/Ti/SiO2/Si(111) 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 δ 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.