Abstract
Inelastic-neutron-scattering measurements were performed on a single crystal of the heavy-fermion paramagnet above its superconducting temperature. We confirm the presence of antiferromagnetic fluctuations with the incommensurate wave-vector . A quasielastic signal is found, whose momentum-transfer dependence is compatible with fluctuations of magnetic moments with a sine-wave modulation of wave-vector 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 . These fluctuations saturate below the temperature , 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 .
- Received 24 June 2021
- Revised 24 August 2021
- Accepted 25 August 2021
DOI:https://doi.org/10.1103/PhysRevB.104.L100409
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