Parity violation in a single domain of spin-triplet Sr2RuO4 superconductors

We observed an unconventional parity-violating vortex in single domain Sr2RuO4 single crystals using a transport measurement. The current–voltage characteristics of submicron Sr2RuO4 show that the induced voltage has anomalous components which are even functions of the bias current. The results may suggest that the vortex itself has a helical internal structure characterized by a Hopf invariant (a topological invariant). We also discuss that the hydrodynamics of such a helical vortex causes the parity violation to retain the topological invariant.