Low-dimensional antiferromagnetic fluctuations in the heavy-fermion paramagnetic ladder compound UTe2

Inelastic-neutron-scattering measurements were performed on a single crystal of the heavy-fermion paramagnet UTe2 above its superconducting temperature. We confirm the presence of antiferromagnetic fluctuations with the incommensurate wave-vector k(1) = (0, 0.57, 0). A quasielastic signal is found, whose momentum-transfer dependence is compatible with fluctuations of magnetic moments mu parallel to a with a sine-wave modulation of wave-vector k(1) and in-phase moments on the nearest U atoms. Low dimensionality of the magnetic fluctuations, consequence of the ladder structure, is indicated by weak correlations along the direction c. These fluctuations saturate below the temperature T-1 similar or equal to 15 K, in possible relation with anomalies observed in thermodynamic, electrical-transport, and nuclear-magnetic-resonance measurements. The absence or weakness of ferromagnetic fluctuations in our data collected at temperatures down to 2.1 K and energy transfers from 0.6 to 7.5 meV is emphasized. These results constitute constraints for models of magnetically mediated superconductivity in UTe2.

Automated summary

Inelastic neutron scattering measurements on a single crystal of heavy-fermion paramagnet UTe2 revealed the presence of antiferromagnetic fluctuations with specific characteristics. Weak correlations and saturation temperature of the magnetic fluctuations were highlighted as key findings in this study, providing constraints for models of magnetically mediated superconductivity in UTe2.