PHENOMENOLOGY OF NUCLEAR-SPIN RELAXATION IN HIGH-TC SUPERCONDUCTORS

We propose a simple phenomenological approach for the nuclear spin relaxation rate R(S) and the density of states for excitations N(S), which results from a natural simplification of Eliashberg equations. Near T(c) the peak in density of states N(S) is related to the quasi-particle relaxation rate, not to the superconducting gap. The resulting experimental value of this rate is in good agreement with the relaxation time from conductivity. The experimental lack of coherence peak and the strong decrease of R(S) below T(c) are explained by the same value of this rate. Therefore all the various independent experimental data that we have considered can be explained in a completely coherent way.