Local NMR relaxation rates T1-1 and T2-1 depending on the d -vector symmetry in the vortex state of chiral and helical p -wave superconductors

Local NMR relaxation rates in the vortex state of chiral and helical p-wave superconductors are investigated by the quasiclassical Eilenberger theory. We calculate the spatial and resonance frequency dependences of the local NMR spin-lattice relaxation rate T-1(-1) and spin-spin relaxation rate T-2(-1). Depending on the relation between the NMR relaxation direction and the d-vector symmetry, the local T-1(-1) and T-2(-1) in the vortex core region show different behaviors. When the NMR relaxation direction is parallel to the d-vector component, the local NMR relaxation rate is anomalously suppressed by the negative coherence effect due to the spin dependence of the odd- frequency s-wave spin-triplet Cooper pairs. The difference between the local T-1(-1) and T-2(-1) in the site-selective NMR measurement is expected to be a method to examine the d-vector symmetry of candidate materials for spin-triplet superconductors.