The nuclear spin relaxation rate for clean quasi-two-dimensional superconductors in the vicinity of

Abstract

We calculate the nuclear spin relaxation rate of clean quasi-two-dimensional (2D) superconductors with s-wave pairing in high magnetic fields using the BCS model and the Brandt, Pesch and Tewordt approximation for the single-particle propagator. The calculation is valid in the vicinity of . Thermal fluctuations of vortices are not taken into account. We evaluate numerically our results in the case of high- materials and organic superconductors. In a perpendicular field the Hebel - Slichter coherence peak is suppressed depending on the variation of the quasi-particle lifetime below . We also describe the magnetic field dependence of the nuclear spin relaxation rate. Using the experimentally determined value of the quasi-particle lifetime, the model reproduces the experimental initial variations of versus at different magnetic fields. However, the Hebel - Slichter peak is conserved in the low-field limit, or when the applied magnetic field is parallel to the superconducting planes.