Effect of deposition time on multiferroic properties of sputtered Bi_0.9La_0.1Fe_0.9Mn_0.1O₃ films

Single-phase Bi_0.9La_0.1Fe_0.9Mn_0.1O₃ (BLFMO) films were successfully deposited on Pt(111)/Ti/SiO₂/Si(100) substrates by radio frequency magnetron sputtering. The time-dependent structural and multiferroic properties of BLFMO films were examined. The X-ray diffraction patterns and micro-Raman spectra confirmed the formation of pure phase, rhombohedral structure in BLFMO. All the films had highly (012) and (024) preferred orientations. SEM images of BLFMO films exhibited dense and uniform microstructures with grain sizes of approximately 90–100 nm. The data of ferroelectric test indicated that the double remanent polarization (2P _r ) value of the BLFMO film with a thickness of 412 nm was 110 μC/cm² at an applied electric field of 218 kV/cm. The leakage current density versus electric field curves of BLFMO films indicated that the leakage current decreased monotonically with the increase of sputtering time at a given electric field due to the decrease in total number of free carriers. Magnetism test indicated that the saturation magnetization of BLFMO films was higher when the film thickness was thinner. The results demonstrated that film thickness or deposition time had an effect on multiferroic properties of BLFMO films.