Electronic theory for the magnetic anisotropy in Sr2RuO 4

Using a three-band Hubbard Hamiltonian we calculated within the random-phase-approximation the spin susceptibility, χ(q, ω), and NMR spin-lattice relaxation rate 1/T1, in the normal state of the triplet superconductor Sr2RuO4, and obtained quantitative agreement with experimental data. Most importantly, we found that because of spin-orbit coupling the out-of-plane component of the spin susceptibility χzz(q, ω) becomes two times larger than the in-plane one at low temperatures. We analyze in particular the role of the xy-band in the magnetic anisotropy. © 2002 Plenum Publishing Corporation