Observation of possible quantum interference effects in SrRuO 3 epitaxial thin films grown by high-oxygen pressure dc sputtering

Abstract

A careful study of the electronic transport and magnetotransport properties of metallic ferromagnetic SrRuO 3 (SRO) thin films is reported. Epitaxial (∼150 nm) SRO films were grown on (001)-oriented SrTiO 3 (STO) substrates by dc sputtering technique at high oxygen pressure. Resistivity measurements were performed up to temperatures as low as 2 K in magnetic fields strengths of up to 9 T, applied perpendicular to the film plane. The films featured excellent metallic behavior at room temperature, with a resistivity, ρ(300 K) < 600 μΩ cm. The presence of minima in the ρ– T plots at ∼4 K was clearly detected from these measurements. The 9 T magnetic field did not remove the minima signaling its nonmagnetic origin In addition, the ρ(μ 0 H = 9 T, T) minima was slightly shifted to higher temperature and the ρ(μ 0 H = 9 T, T ≤ 4 K) was larger when it was compared with ρ(μ 0 H = 0 T, T ≤ 4 K). Increasing relevance of quantum corrections to the conductivity as the temperature is lowered has been invocated as possible cause of this anomalous electrical behavior. In this case, effects arising from quantum interference of the electronic wavelength are expected. Weak localization and renormalized electron–electron interaction have been considered as possible sources giving rise to quantum correction to the conductivity.