Nuclear relaxation rates, penetration depth, and energy-dependent gap functions in high-Tc superconductors

In this paper, the authors study the experimental consequences of a gap function which is odd in energy. This type of gap may occur in high temperature superconductors. The authors show that nuclear spin relaxation experiments can be used to probe the particle-hole parity of a gap function. The authors 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 (α T2-α/α) and the electromagnetic penetration depth (αT(1-/α)