Probing pairing symmetry in Sr2RuO4

We study the spin dynamics in a p-wave superconductor at the nesting vector associated with the α- and β-bands in Sr2RuO4. We find a collective mode at the nesting vector in the superconducting phase identified as the odd-parity pairing state which breaks time-reversal symmetry. This mode in the 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 pairing symmetry in Sr2RuO4. (author)