# Coexistence of ferromagnetic fluctuations and superconductivity in the actinide superconductor UTe2

## TL;DR

This study uses muon spin relaxation to show that UTe2 exhibits persistent magnetic fluctuations that coexist with superconductivity below 1.6 K, with no magnetic order detected down to 0.025 K.

## Contribution

It provides direct experimental evidence of coexistence of ferromagnetic fluctuations and superconductivity in UTe2, a novel finding for actinide superconductors.

## Key findings

- Magnetic fluctuations persist below Tc without long-range order.
- Superconductivity coexists with ferromagnetic fluctuations.
- Magnetic fluctuation behavior aligns with weak itinerant ferromagnetic metals.

## Abstract

We report low-temperature muon spin relaxation/rotation (muSR) measurements on single crystals of the actinide superconductor UTe2. Below 5 K we observe a continuous slowing down of magnetic fluctuations that persists through the superconducting (SC) transition temperature (Tc = 1.6 K), but we find no evidence of long-range or local magnetic order down to 0.025 K. The temperature dependence of the dynamic relaxation rate down to 0.4 K agrees with the self-consistent renormalization theory of spin fluctuations for a three-dimensional weak itinerant ferromagnetic metal. Our muSR measurements also indicate that the superconductivity coexists with the magnetic fluctuations.