Probing pairing symmetry in Sr2RuO4

We study the spin dynamics in a p-wave superconductor at the nesting vector associated with the alpha- and beta-bands in Sr2RuO4 We find a collective mode at the nesting vector in the superconducting phase identified as the o dd-parity pairing state which breaks time-reversal symmetry. This mode in t he spin channel exists only in a p-wave superconductor, not in s- or d-wave superconductors. We propose that probing this mode would clarify the pairi ng symmetry in Sr2RuO4.