Emergent magnetic phase transitions in Fe-doped SrTiO_{3- δ}

In defect engineering, both cation doping and oxygen vacancies play key roles in deciding the properties of oxide, and the utilization of their cooperation has attracted much interest in recent years. Here, we report an emergent magnetic phase transition near 18 K in Fe-doped SrTiO_3-δ by utilizing the magnetic interactions between the doped Fe cations and oxygen vacancies. The effects of Fe dopants and oxygen vacancies on the structural and magnetic properties were characterized by a high-resolution X-ray diffraction, Raman spectroscopy, and superconducting quantum interference device. In particular, as the temperature rises across the magnetic phase transition, the coercivity of Fe-SrTiO_3-δ decreases from ∼7700 Oe at 2 K to ∼104 Oe at 19 K. Our results of creating emergent magnetic phases with the coeffects of both cation dopants and oxygen vacancies could pave a way to inducing novel quantum states in epitaxial films on Fe-SrTiO_3-δ single crystal substrates with the magnetic proximity effect.