Tuning Magnetic Properties of BiFeO3Thin Films by Controlling Rare-Earth Doping: Experimental and First-Principles Studies

Rare-earth (RE)-doped BiFeO3(BFO) thin films were grown on LaAlO3(LAO) substrates by using pulsed laser deposition technique. All of the BFO films doped with 10% of RE exhibit a rhombohedral single phase. As for the Pr and Nd doping cases, the ferromagnetic phase is less favored because the Fe2+amount is not dominant. When dopant concentration was increased to 20%, the RE-doped BFO films go through a structural transition from rhombohedral to pure orthorhombic phase (for Ho, Sm), a mixed phase of orthorhombic and tetragonal (for Pr, Nd), or pure tetragonal (for Eu). As an important consequence, magnetic properties of RE-doped BFO films have drastically changed. Our results give a guide for how to tailor the ferromagnetism of BFO films by appropriate controlling the type of RE dopant as well as dopant concentration. The experimental findings are completed by performing density functional theory calculations to explore the effect of RE doping in BFO for the considered three phases.