Theory of vortex excitation imaging via an NMR relaxation measurement

The temperature dependence of the site-dependent nuclear spin relaxation time T-1 around vortices is studied in s-wave and d-wave superconductors. Reflecting low-energy electronic excitations associated with the vortex core, temperature dependences deviate from those of the zero-field case, and T-1 becomes faster when approaching the vortex core. In the core region, T-1(-1) has a new peak below T-c. The NMR study by the resonance field dependence may be a new method to prove the spatial resolved vortex core structure in various superconductors.