The multiferroic properties of polycrystalline Bi1−xYxFeO3 films

Polycrystalline Bi1−xYxFeO3 films with varying x from 0 to 0.30 were prepared by pulsed laser deposition on surface oxidized Si (100) substrates with LaNiO3 as buffer layer. The influence of Y doping on the structure, ferroelectric properties, and exchange bias have been systematically investigated. X-ray diffraction and Raman spectroscopy studies revealed the structural transition from rhombohedral R3c to orthorhombic Pn21a with increasing x above 0.10. The leakage current density of BiFeO3 has been effectively suppressed by Y doping, and well saturated P–E loops have been observed in Bi1−xYxFeO3 (0.01 ≤ x ≤ 0.07). Exchange bias field with a 3.6 nm thick NiFe layer increases with increasing x to 0.01, then decreases with further increasing x.