Effect of spin-orbit coupling on the -vector in SrRuO

Nomura, Takuji; Ikeda, Hiroaki*

We investigate the effect of the spin-orbit coupling on the -vector state from the viewpoint of a microscopic theory. The pairing interaction is evaluated by the third-order perturbation theory in Coulomb integrals at Ru sites, where the spin-orbit coupling among Ru4d electrons is fully included. Consequently it is shown that the -vector points perpendicular to the basal RuO planes for realistically small spin-orbit couplings, consistently with experiments.