Fermi-liquid versus non-Fermi-liquid/'strange-metal' fits to the electrical resistivity in the quantum critical magnetic regime of an unconventional superconductor
Abstract
The question of a possible quantum critical point lying inside of a superconducting phase is central for understanding unconventional superconductivity. In various unconventional superconductors, non-Fermi-liquid/'strange-metal' Tn variations, with n<2, of the electrical resistivity have been identified as the signature of magnetic quantum criticality. However, a difficulty is to prove experimentally that a non-Fermi-liquid/'strange-metal' law identified at temperatures above the superconducting temperature is the signature of an intrinsic zero-temperature quantum critical regime. In the heavy-fermion paramagnet UTe2, unconventional superconductivity develops in the vicinity of a metamagnetic quantum phase transition induced by a magnetic field, and the quantum critical magnetic properties are suspected to play a role for the superconducting mechanism. In this work, we present a comparative analysis of electrical resistivity data collected on two UTe2 samples of different qualities, in magnetic fields tilted by angles θ≃35−40~∘ from b to c. Fits to the data have been performed either with a Fermi-liquid function ρ=ρ0+AT2 or with a non-Fermi-liquid/'strange-metal' function ρ=ρ0+AnTn. Near to a superconducting phase induced beyond 40~T, non-physical residual resistivities ρ0<0 are extracted from the Tn fits, revealing that a 'hidden' Fermi-liquid T2 regime may be ultimately recovered at low temperature. The results obtained here highlight the importance to investigate high-quality samples with low residual resistivity to confirm - or not - the presence of a suspected 'hidden' quantum critical behavior masked by superconductivity.
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BibTeX
@misc{knafo2026fermiliquid,
title = {{Fermi-liquid versus non-Fermi-liquid/'strange-metal' fits to the electrical resistivity in the quantum critical magnetic regime of an unconventional superconductor}},
author = {William Knafo and T. Thebault and K. Somesh and G. Lapertot and G. Knebel and D. Braithwaite and D. Aoki},
howpublished = {HAL},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2604.14952},
eprint = {2604.14952},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05845885v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Fermi-liquid versus non-Fermi-liquid/'strange-metal' fits to the electrical resistivity in the quantum critical magnetic regime of an unconventional superconductor
AU - William Knafo
AU - T. Thebault
AU - K. Somesh
AU - G. Lapertot
AU - G. Knebel
AU - D. Braithwaite
AU - D. Aoki
PY - 2026
DA - 2026/10/30
PB - HAL
DO - 10.48550/arxiv.2604.14952
UR - https://hal.science/hal-05845885v1
AB - The question of a possible quantum critical point lying inside of a superconducting phase is central for understanding unconventional superconductivity. In various unconventional superconductors, non-Fermi-liquid/'strange-metal' T^n variations, with n<2, of the electrical resistivity have been identified as the signature of magnetic quantum criticality. However, a difficulty is to prove experimentally that a non-Fermi-liquid/'strange-metal' law identified at temperatures above the superconducting temperature is the signature of an intrinsic zero-temperature quantum critical regime. In the heavy-fermion paramagnet UTe_2, unconventional superconductivity develops in the vicinity of a metamagnetic quantum phase transition induced by a magnetic field, and the quantum critical magnetic properties are suspected to play a role for the superconducting mechanism. In this work, we present a comparative analysis of electrical resistivity data collected on two UTe_2 samples of different qualities, in magnetic fields tilted by angles θ≃35−40~^∘ from b to c. Fits to the data have been performed either with a Fermi-liquid function ρ=ρ_0+AT^2 or with a non-Fermi-liquid/'strange-metal' function ρ=ρ_0+A_nT^n. Near to a superconducting phase induced beyond 40~T, non-physical residual resistivities ρ_0<0 are extracted from the T^n fits, revealing that a 'hidden' Fermi-liquid T^2 regime may be ultimately recovered at low temperature. The results obtained here highlight the importance to investigate high-quality samples with low residual resistivity to confirm - or not - the presence of a suspected 'hidden' quantum critical behavior masked by superconductivity.
ER -