Tunable Magnetic Properties in Sr 2 FeReO 6 Double-Perovskite.

Double-perovskite oxides have attracted recent attention due to their attractive functionalities and application potential. In this paper, we demonstrate the effect of dual controls, i.e., the deposition pressure of oxygen ( P O 2 ) and lattice mismatch (ε), on tuning magnetic properties in epitaxial double-perovskite Sr 2 FeReO 6 films. In a nearly lattice matched Sr 2 FeReO 6 /SrTiO 3 film, the ferrimagnetic-to-paramagnetic phase transition occurs when P O 2 is reduced to 30 mTorr, probably due to the formation of Re 4+ ions that replace the stoichiometric Re 5+ to cause disorders of B-site ions. On the other hand, a large compressive strain or tensile strain shifts this critical P O 2 to below 1 mTorr or above 40 mTorr, respectively. The observations can be attributed to the modulation of B-site ordering by epitaxial strain through affecting elemental valence. Our results provide a feasible way to expand the functional tunability of magnetic double-perovskite oxides that hold great promise for spintronic devices.