Fermi-liquid versus non-Fermi-liquid/'strange-metal' fits to the electrical resistivity in the quantum critical magnetic regime of an unconventional superconductor
Year: 2026
Type: preprint
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' $T^{n}$ 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 $θ\simeq35-40$~$^\circ$ from $\mathbf{b}$ to $\mathbf{c}$. 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.
Source: arXiv (Cornell University)
Institutions: Centre National de la Recherche Scientifique, Institut National des Sciences Appliquées de Toulouse, Laboratoire National des Champs Magnétiques Intenses, Institute for Materials Research, Tohoku University, Karlsruhe Institute of Technology, Institut polytechnique de Grenoble, Commissariat à l'Énergie Atomique et aux Énergies Alternatives, CEA Grenoble, Institut de Recherche Interdisciplinaire de Grenoble
Language: English
Subfield: Condensed Matter Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7154747458