Structural transition and multiferroic properties of Eu-doped BiFeO ₃ thin films

The Bi_1-xEu_xFeO₃ (x=0, 0.05, 0.10, 0.15, 0.20, and 0.30) thin films were grown by pulsed laser deposition on Pt/Ti/SiO₂/Si substrates, and the effects of Eu content on the structure and multiferroic properties were investigated. A structural transition from rhombohedral R3c to orthorhombic Pbnm occurred in the film with x=0.15 due to the increase of the Eu content. Superior multiferroic properties were obtained in the film with x=0.10, giving a remanent polarization P _r=74 μC/cm² and a coercive field E_c=250 kV/cm at an applied electric field E=560 kV/cm, a good antifatigue property, and a saturated magnetization M_s=3.5 emu/cm³. These significantly improved ferroelectric properties could be attributed to the appropriate lattice distortion and the lower leakage current due to the doping, while the enhanced ferromagnetism might be ascribed to the substitution-induced suppression of the spiral spin modulation.