Spin-lattice relaxation for point-node-like s-wave superconductivity in f-electron systems

In this study, we examined the temperature dependence of the spin-lattice relaxation using an f-d-p model, which is an effective model of UTe2. Solving the linearized Eliashberg equation in the f-d-p model based on third-order perturbation theory, we obtain a point-node-like s-wave pairing state. Our result shows that the Hebel-Slichter peak in the point-node-like s-wave pairing state is smaller than that in the isotropic s-wave pairing state. However, the Hebel-Slichter peak remains robust even in the point-node-like s-wave pairing state, and the point-node-like s-wave state is inconsistent with the results of nuclear magnetic resonance measurements.