O17NMR Evidence for Orbital Dependent Ferromagnetic Correlations inSr2RuO4

We probed spin correlations in Ru ${4d}_{\mathrm{xy}}$ and ${4d}_{yz,zx}$ orbitals separately in the unconventional metallic state of ${\mathrm{Sr}}_2{\mathrm{RuO}}_4$ by ${}^{17}\mathrm{O}$ NMR. We establish that spin correlations are orbital dependent, and only the Ru ${4d}_{\mathrm{xy}}$ spin susceptibility ${\chi }_{\mathrm{xy}}$ increases significantly with decreasing temperature prior to the crossover to the canonical Fermi liquid state at $T_{\mathrm{FL}}=25\mathrm{}\mathrm{K}$. The temperature dependence of ${}^{17}\mathrm{O}$ and ${}^{101}\mathrm{Ru}$ nuclear spin-lattice relaxation rates ${}_{}{}^{17,101}{}_{}{}^{}1/T_1$ uncovers interplay between the growth of ferromagnetic spin fluctuations and anomalous charge transport properties.