Evidence of high-spin Ru and universal magnetic anisotropy in SrRuO3 thin films

We have investigated the origins of enhanced saturated magnetic moment and strong strain-dependent magnetic anisotropy in epitaxial films of the transition-metal oxide SrRuO3. We find evidence for an enhancement of the carrier concentration and the stabilization of high-spin Ru4+. Through x-ray magnetic circular dichroism measurements, we also observe a strain-dependent enhancement of the out-of-plane orbital magnetic moment. Such an enhancement is consistent with the universal out-of-plane anisotropy axis shown to occur in films in a variety of different crystallographic orientations. We explain all these effects in terms of an anisotropic reduction in the crystal field resulting from anisotropically reduced orbital overlap in distorted films.