dorsal/arxiv
View SchemaVanishing Phase Stiffness and Fluctuation-Dominated Superconductivity: Evidence for Inter-Band Pairing in UTe$_2$
| Authors | Sahas Kamat, Jared Dans, Shanta Saha, Daniel F. Agterberg, Johnpierre Paglione, B. J. Ramshaw |
|---|---|
| Categories | |
| ArXiv ID | 2601.09138vv1 |
| URL | https://arxiv.org/abs/2601.09138 |
| License | http://creativecommons.org/licenses/by/4.0/ |
Abstract
Superconductivity in three dimensions is almost universally governed by Ginzburg-Landau mean field theory, with critical fluctuations typically confined to within a few percent of the transition temperature ($T_{\rm c}$). We report that the heavy-Fermion superconductor UTe$_2$ exhibits a fluctuation regime that extends over a temperature range as wide as $T_{\rm c}$ itself -- the largest observed for any three-dimensional superconductor. Through ultrasound measurements of the elastic moduli and sound attenuation, we find that UTe$_2$ transitions from a mean-field-like state at ambient pressure to a fluctuation dominated state at higher pressures. This regime is marked by elastic softening and an increase in sound attenuation that onsets well above $T_{\rm c}$, with the attenuation remaining anomalously high deep in the superconducting state. Our analysis shows that these features stem from an extremely low superfluid phase stiffness. This results in a kinetic inductance as high as that of granular aluminum, but achieved in the clean limit. We propose that this exotic state is driven by dominant inter-band pairing mediated by ferromagnetic fluctuations, leading to "local" cooper pairs with a coherence length of only a few lattice constants.
{
"annotation_id": "7af27faa-1289-413e-ac87-dcaaafc5a066",
"date_created": "2026-02-17T05:53:20.065000Z",
"date_modified": "2026-02-17T05:53:20.065000Z",
"file_hash": "647c247903379a2533ab2e7ab1ca124737bdd6433d59bb4a5925510407e86871",
"private": false,
"record": {
"abstract": "Superconductivity in three dimensions is almost universally governed by Ginzburg-Landau mean field theory, with critical fluctuations typically confined to within a few percent of the transition temperature ($T_{\\rm c}$). We report that the heavy-Fermion superconductor UTe$_2$ exhibits a fluctuation regime that extends over a temperature range as wide as $T_{\\rm c}$ itself -- the largest observed for any three-dimensional superconductor. Through ultrasound measurements of the elastic moduli and sound attenuation, we find that UTe$_2$ transitions from a mean-field-like state at ambient pressure to a fluctuation dominated state at higher pressures. This regime is marked by elastic softening and an increase in sound attenuation that onsets well above $T_{\\rm c}$, with the attenuation remaining anomalously high deep in the superconducting state. Our analysis shows that these features stem from an extremely low superfluid phase stiffness. This results in a kinetic inductance as high as that of granular aluminum, but achieved in the clean limit. We propose that this exotic state is driven by dominant inter-band pairing mediated by ferromagnetic fluctuations, leading to \"local\" cooper pairs with a coherence length of only a few lattice constants.",
"arxiv_id": "2601.09138",
"authors": [
"Sahas Kamat",
"Jared Dans",
"Shanta Saha",
"Daniel F. Agterberg",
"Johnpierre Paglione",
"B. J. Ramshaw"
],
"categories": [
"cond-mat.supr-con",
"cond-mat.str-el"
],
"license": "http://creativecommons.org/licenses/by/4.0/",
"title": "Vanishing Phase Stiffness and Fluctuation-Dominated Superconductivity: Evidence for Inter-Band Pairing in UTe$_2$",
"url": "https://arxiv.org/abs/2601.09138",
"version": "v1"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "8aec331f-7189-4eb2-a5b0-20f1559a3070",
"id": "arXiv Dataset",
"type": "Model",
"variant": "snapshot-2026-01-17",
"version": "0.1.0"
},
"user_id": 1000002
}