Magnetoresistance Versus Oxygen Deficiency in Epi-stabilized SrRu(1 − x)Fe (x)O(3 − δ) Thin Films

Oxygen vacancies have a profound effect on the magnetic, electronic, and transport properties of transition metal oxide materials. Here, we studied the influence of oxygen vacancies on the magnetoresistance (MR) properties of SrRu(1 − x)Fe(x)O(3 - δ) epitaxial thin films (x = 0.10, 0.20, and 0.30). For this purpose, we synthesized highly strained epitaxial SrRu(1 − x)Fe(x)O(3 − δ) thin films with atomically flat surfaces containing different amounts of oxygen vacancies using pulsed laser deposition. Without an applied magnetic field, the films with x = 0.10 and 0.20 showed a metal–insulator transition, while the x = 0.30 thin film showed insulating behavior over the entire temperature range of 2–300 K. Both Fe doping and the concentration of oxygen vacancies had large effects on the negative MR contributions. For the low Fe doping case of x = 0.10, in which both films exhibited metallic behavior, MR was more prominent in the film with fewer oxygen vacancies or equivalently a more metallic film. For semiconducting films, higher MR was observed for more semiconducting films having more oxygen vacancies. A relatively large negative MR (~36.4%) was observed for the x = 0.30 thin film with a high concentration of oxygen vacancies (δ = 0.12). The obtained results were compared with MR studies for a polycrystal of (Sr(1 − x)La(x))(Ru(1 − x)Fe(x))O(3). These results highlight the crucial role of oxygen stoichiometry in determining the magneto-transport properties in SrRu(1 − x)Fe(x)O(3 − δ) thin films.