Theory of vortex excitation imaging via an NMR relaxation measurement

TL;DR

This paper investigates how the nuclear spin relaxation time T_1 varies around vortices in superconductors, revealing temperature-dependent behaviors that can help image vortex core structures using NMR techniques.

Contribution

It introduces a novel approach to visualize vortex cores in superconductors through temperature-dependent NMR relaxation measurements.

Findings

T_1 decreases near vortex cores with temperature

T_1^{-1} exhibits a new peak below T_c in the core region

Resonance field dependence in NMR can spatially resolve vortex structures

Abstract

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 with 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.