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

TL;DR

This paper investigates the spin-lattice relaxation in a model of UTe2, revealing that a point-node-like s-wave pairing state exhibits a reduced but still present Hebel-Slichter peak, which conflicts with experimental NMR results.

Contribution

It introduces a theoretical analysis of spin-lattice relaxation in a specific f-electron superconductor using Eliashberg theory, highlighting discrepancies with experimental data.

Findings

The Hebel-Slichter peak is smaller in the point-node-like s-wave state.

The peak remains robust despite nodal features.

The model's predictions are inconsistent with NMR measurements.

Abstract

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.