NUCLEAR RELAXATION RATES, PENETRATION DEPTH, AND ENERGY-DEPENDENT GAP FUNCTIONS IN HIGH-Tc SUPERCONDUCTORS

We study the experimental consequences of a gap function which is odd in energy. This type of gap may occur in high temperature superconductors. We show that nuclear spin relaxation experiments can be used to probe the "particle-hole parity" of a gap function. We find that an exponent α=1/3 which characterizes the energy dependence is in agreement with the currently available experimental data of both the nuclear spin relaxation rate (∝T(2-α)/α) and the electromagnetic penetration depth (∝T(1-α)/α).