Observation of possible quantum interference effects in SrRuO_3 epitaxial thin films grown by high-oxygen pressure dc sputtering

摘要

A careful study of the electronic transport and magnetotransport properties of metallic ferromagnetic SrRuO_3 (SRO) thin films is reported. Epitaxial (approx 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 9T, applied perpen-dicular to the film plane. The films featured excellent metallic behavior at room temperature, with a resistivity, p(300 K) < 600 mu Ω cm. The presence of minima in the p-T plots at approx 4K was clearly detected from these measurements. The 9 T magnetic field did not remove the minima signaling its nonmagnetic origin In addition, the p(mu_oH = 9 T,T) minima was slightly shifted to higher temperature and the p(mu_oH = 9 T,T < 4 K) was larger when it was compared with p(mu_oH = 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.