μ^+$ Knight shift in UTe2: Evidence for relocalization in a Kondo lattice

• Published in: Physical review. B 2023-08, Vol.108 (8)
• Main Authors: Azari, Nasrin, Goeks, Mariah R., Yakovlev, M., Abedi, Mae, Dunsiger, Sarah R., Thomas, Sean Michael, Thompson, Joe David, Rosa, Priscila F. S., Sonier, Jeff E.
• Format: Article
• Language: English
• Subjects: Kondo effect; magnetic interactions; MATERIALS SCIENCE; spin-triplet pairing
• ISSN: 2469-9950
• DOI: 10.1103/PhysRevB.108.L081103

The local magnetic susceptibility of the spin-triplet superconductor UTe2 has been investigated by positive muon (μ+) Knight shift measurements in the normal state. Three distinct μ+ Knight shift components are observed for a magnetic field applied parallel to the c axis. Two of these exhibit a breakdown in the linear relationship with the bulk magnetic susceptibility (χ) below a temperature T*~30K, which points to a gradual emergence of a correlated Kondo liquid. Below Tr~12K linearity is gradually restored, indicating relocalization of the Kondo liquid quasiparticles. The third Knight shift component is two orders of magnitude larger, and despite the c-axis alignment of the external field, scales with the a axis χ above Tr~12K. We conjecture that this component is associated with magnetic clusters and the change in the temperature dependence of all three Knight shift components below Tr is associated with a change in magnetic correlations. Finally, our findings indicate that prior to the onset of superconductivity the development of the itinerant heavy-electron fluid is halted by a gradual development of local U 5⁢ƒ-moment fluctuations.