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In this work, the magnetotransport properties of epitaxial Sr 1- x La x Ru 1- x Fe x O 3 ( x = 0.05, 0.10, 0.20, and 0.30) thin films grown by pulsed laser deposition on SrTiO 3 (001) substrates were investigated. Compared to doping Fe into the Ru 4+ site of SrRuO 3 , doping LaFeO 3 into SrRuO 3 resulted in an increase in the zero-field resistivity. A larger zero-field resistivity value in magnetic perovskite oxide is, in many cases, favorable for obtaining high magnetoresistance. The films (0.0 ≤ x ≤ 0.10) showed metallic behavior and ferromagnetic ordering, although the resistivity increased and the ferromagnetic transition temperature T C decreased with an increase in x . The thin film with x = 0.20 displayed a clear metal-to-insulator phase transition at low temperature and also displayed a well-defined resistivity minimum. This upturn in the resistivity curve is associated with the large electron-electron interaction present in the material. The magnetoresistance values increased as x increased, and we observed a large negative magnetoresistance (MR = −35%) for the thin film with x = 0.30. The observed high MR values are associated with spin fluctuation of the mobile electronic carriers in the material. [ABSTRACT FROM AUTHOR]

SrRu 1− x Fe x O 3−δ ( x = 0.00, 0.05, 0.10, and 0.20) thin films were fabricated to study the intrinsic aspects of a “self spin valve”. Using epitaxial strain and high oxygen partial pressure during thin film growth, single phase thin films with negligible oxygen vacancies were successfully grown, and problems related to A-site disorder and grain boundaries were minimized. Under application of an external magnetic field of up to 9 T, the resistivity of all films decreased, resulting in large negative magnetoresistance (up to ∼14.4%), which was stronger at temperatures in the range 10–30 K. An abrupt metal-insulator transition at T ∼ 43 K was found in the x = 0.20 film, which was explained using a two-fluid model related to electron–electron interactions. From the model, two fitting parameters were found to be necessary for in-situ and homogenous defects, while three or unphysical fitting parameters were necessary for ex-situ and inhomogeneous defects. [ABSTRACT FROM AUTHOR]