Anisotropic pairing in superconducting<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Sr</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">RuO</mml:mi></mml:mrow><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow><mml:mo>:</mml:mo></mml:math>Ru NMR and NQR studies

Ru NMR and nuclear quadrupole resonance studies are reported on single-crystal ${\mathrm{Sr}}_{2}{\mathrm{RuO}}_{4}$ ${(T}_{c}=$0.7 K) with the same layered perovskite structure as ${\mathrm{La}}_{2}{\mathrm{CuO}}_{4}$. The Pauli spin susceptibility deduced from the Ru Knight shift is found to be largely enhanced by a factor of $\ensuremath{\sim}$5.4 as compared with the value from the band calculation. In the superconducting state, the nuclear spin-lattice relaxation rate ${1/T}_{1}$ exhibits a sharp decrease with no coherence peak just below ${T}_{c}$ and the ${T}_{1}T$=constant behavior well below ${T}_{c},$ suggesting that the anisotropic pairing state is realized as in heavy-fermion and high-${T}_{c}$ superconductors.