Non-Fermi liquid behaviour below the Néel temperature in the frustrated heavy Fermion magnet UAu2

Christopher D. O'Neill*, Julian L Schmehr, Harry D. J. Keen, Luke Pritchard Cairns, Dmitry A Sokolov, Andreas Hermann, Didier Wermeille, Pascal Manuel, Frank Kruger, Andrew D. Huxley*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The term Fermi liquid is almost synonymous with the metallic state. The association is known to break down at quantum critical points (QCPs), but these require precise values of tuning parameters, such as pressure and applied magnetic field, to exactly suppress a continuous phase transition temperature to the absolute zero. Three-dimensional non-Fermi liquid states, apart from superconductivity, that are unshackled from a QCP are much rarer and are not currently well understood. Here, we report that the triangular lattice system uranium diauride (UAu2) forms such a state with a non-Fermi liquid low-temperature heat capacity C/T∼log (1/T) and electrical resistivity ρ(T)−ρ(0)∝T1.35 far below its Néel temperature. The magnetic order itself has a novel structure and is accompanied by weak charge modulation that is not simply due to magnetostriction. The charge modulation continues to grow in amplitude with decreasing temperature, suggesting that charge degrees of freedom play an important role in the non-Fermi liquid behavior. In contrast with QCPs, the heat capacity and resistivity we find are unusually resilient in magnetic field. Our results suggest that a combination of magnetic frustration and Kondo physics may result in the emergence of this novel state.
Original languageEnglish
Article numbere2102687118
JournalProceedings of the National Academy of Sciences (PNAS)
Issue number49
Publication statusPublished - 7 Dec 2021


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