We report the significant improvement of the ferroelectric properties of $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ thin film through control of electrical leakage by Nb doping. A very large remanent electrical polarization value of $80\mu \mathrm{C}∕{\mathrm{cm}}^2$ was observed in ${\mathrm{Bi}}_{0.8}{\mathrm{La}}_{0.2}{\mathrm{Nb}}_{0.01}{\mathrm{Fe}}_{0.99}{\mathrm{O}}_3$ thin film on $\mathrm{Pt}∕\mathrm{Ti}∕\mathrm{Si}{\mathrm{O}}_2∕\mathrm{Si}$ substrate. The doping effect of Nb in reducing the movable charge density due to oxygen vacancies in $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ was confirmed by the dielectric measurements. A very small loss was observed in the Nb and La codoped $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ thin film. As well as the improvement in the ferroelectric properties, the magnetic moment was also enhanced due to the doping of La.

• Received 30 November 2007

DOI:https://doi.org/10.1103/PhysRevB.77.092101