O17 NMR Observation of Universal Behavior of Ferromagnetic Spin Fluctuations in the Itinerant Magnetic System Sr1-xCaxRuO3

We report the first 17O NMR study of spin dynamics in itinerant ferromagnet SrRuO3 ( TC=160 K) and Ca-doped variant Sr1-xCaxRuO3 for x=0.6 ( TC=24 K) and x=1 (exchange enhanced paramagnet). We observed robust ferromagnetic spin fluctuations for all concentrations including CaRuO3, even though the sign of Weiss temperature crosses over from positive to negative above x∼0.7. At elevated temperatures, ferromagnetic spin fluctuations exhibit a universal behavior.