Charge transfer and magnetotransport properties of Sr1-xLaxRu1-xCoxO3 epitaxial thin films

Abstract

We studied the electronic and magnetotransport properties of Sr1-xLaxRu1-xCoxO3 epitaxial thin films (0 ≤ x ≤ 0.30) grown on atomically flat SrTiO3 (001) substrates. The epitaxial strain from the SrTiO3 substrate would give compressive strain on Sr1-xLaxRu1-xCoxO3 when the film has the same amount of charge transfer as that observed in the bulk sample. If the epitaxial strain applied by the SrTiO3 substrate overrides the charge transfer, it can block half the amount of charge transfer. However, the observed unit cell volume and X-ray photoelectron spectroscopy data clearly reveal that the amount of charge transfer in our epitaxial thin film is approximately the same as that observed in the previously reported bulk samples. The saturation magnetization decreased for all Sr1-xLaxRu1-xCoxO3 thin films, with an increase in the antiferromagnetic behavior. The zero-field resistivity value of all the compositions increased systematically, with a higher resistivity observed at x = 0.30 (ρ(T = 10 K) 450 mΩ cm). A large negative magnetoresistance of up to ∼24.8% was also observed at x = 0.30 (H = 9 T, T = 10 K). We tried to explain our data in terms of super exchange interaction added to existing double exchange interaction between Ru–Co networks.