Effects of La-doping on structural, electrical and multiferroic properties of Bi6Fe2Ti3O18 thin films

Bi6Fe2Ti3O18 (BFTO) and La-doped Bi6-xLaxFe2Ti3O18 (BLFT) (x = 0.03; BLFT3, x = 0.06; BLFT6 and 0.09; BLFT9) thin films were prepared on Pt(111)/Ti/SiO2/Si(100) substrates by using a chemical solution deposition method. All thin films were crystallized in a polycrystalline orthorhombic structures confirmed by X-ray diffraction and Raman spectroscopy. A low order of leakage current density 2.05 x 10(-4) A/cm(2) and improved ferroelectric properties, such as large remnant polarization (2P (r) ) of 19.5 mu C/cm(2) with low coercive filed of 300 kV/cm at an applied electric field of 410 kV/cm, were observed for the BLFT6 thin film. The improved properties for the BLFT thin films were correlated to the reduction of oxygen vacancies, the structural distortion and the stabilization of perovskite structures by the La-ion doping into the Bi-site of the BFTO. At room temperature, the BLFT6 and the BLFT9 thin films showed ferromagnetism, while the BFTO and the BLFT3 thin films showed anti-ferromagnetism.