Electronic theory for the normal-state spin dynamics in Sr2RuO4:: Anisotropy due to spin-orbit coupling -: art. no. 220502

Using a three-band Hubbard Hamiltonian we calculate within the random-phase approximation the spin susceptibility, chi(q,omega), and nuclear magnetic resonance spin-lattice relaxation rate, 1/T-1, in the normal state of the triplet superconductor Sr2RuO4 and obtain quantitative agreement with experimental data. Most importantly, we find that due to spin-orbit coupling the out-of-plane component of the spin susceptibility chi(zz) becomes at low temperatures two times larger than the in-plane one. As a consequence, strong incommensurate antiferromagnetic fluctuations of the quasi-one-dimensional xz and yz bands point into the z-direction. Our results provide further evidence for the importance of spin fluctuations for triplet superconductivity in Sr2RuO4.