Crystal structure and magnetoresistance of vacancy-ordered perovskite SrV0.3Fe0.7O2.8 at low temperature

Abstract

Vacancy-ordering in perovskite oxides brings a rich variety of structures and accompanying physical properties. Previously, we reported room-temperature magnetoresistance in SrV_0.3Fe_0.7O_2.8 with ordered oxygen vacancies in the primitive perovskite (111)_p plane. In this report, we characterize the structure and physical properties of SrV_0.3Fe_0.7O_2.8 at low temperatures. This compound undergoes a structural phase transition from the rhombohedral phase to the monoclinic phase by cooling down to T_s = 200 K. The transition induces octahedral tilting, affecting its magnetization behaviour: The compound shows weak ferromagnetism with almost zero coercivity above T_s, while the coercivity prominently increases below T_s, keeping its weak ferromagnetism. We also observed an enhancement of magnetoresistance by decreasing temperature, reaching −18% at 130 K and 9 T.