Enhanced multiferroic properties in epitaxial Yb-doped BiFeO3 thin films

We report the enhanced multiferroic properties of a ytterbium (Yb)- doped BiFeO3 thin film (Bi0.85Yb0.15FeO3) deposited on a (001) SrRuO3/(100) SrTiO3 substrate by pulsed laser deposition. The crystal structure, surface morphology, ferroelectric domain structure, and the electrical and magnetic behavior of the epitaxial Bi0.85Yb0.15FeO3 film, 100 nm in thickness, were investigated. The results were compared with those of an undoped BiFeO3 thin film. The x-ray diffraction patterns showed that both films have tetragonal-like crystal structures. Atomic force microscopy showed that the Bi0.85Yb0.15FeO3 and BiFeO3 films have flat and clear surface steps, characteristic of a layer-by-layer growth mechanism. Furthermore, the strip-like ferroelectric domain structures were clearly observed in piezoelectric force microscopy. The Bi0.85Yb0.15FeO3 films had significantly higher remanent polarizations of approximately 73 μC/cm2 and lower leakage currents compared to the BiFeO3 thin film. Ferromagnetic enhancement was also observed in the Bi0.85Yb0.15FeO3 film at room temperature. [graphic not available: see fulltext]