Ferroelectric and magnetic properties of Dy-doped BaTiO3 films

Element substitution of BaTiO3-based compounds has been demonstrated as a powerful way for designing novel electronic materials (such as polar metals and multiferroics). To trigger magnetism into ferroelectric BaTiO3, general substituted elements are magnetic transition metals (such as Mn, Fe, and Co). The doping effect of rare-earth elements (such as Dy) in BaTiO3-based compounds was barely investigated. Here, we report the coexistence of magnetism and electric polarization in epitaxial Dy0.5Ba0.5TiO3 films. The single-crystalline films were synthesized by high-pressure magnetron sputtering. The crystal and electronic structures were characterized by high-resolution x-ray diffraction, x-ray photoemission spectroscopy, and resonant soft x-ray absorption spectroscopy. Room-temperature electric polarization was demonstrated by optical second-harmonic generation. Temperature-dependent magnetic hysteresis loops were measured to reveal the revolution of magnetism on temperature. Surprisingly, it is uncovered that the Curie temperature of electric-polarized Dy0.5Ba0.5TiO3 films is around 100 K, far above the critical temperature of non-polarized DyTiO3 (near 60 K). Our work provides another view to understand the magnetoelectric materials.