Revealing isotropic abundant low-energy excitations in UTe$_2$ through complex microwave surface impedance

Fuente: arXiv
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Autori principali: Carlton-Jones, Arthur, Suarez, Alonso, Eo, Yun-Suk, Hayes, Ian M., Saha, Shanta R., Paglione, Johnpierre, Butch, Nicholas P., Anlage, Steven M.
Natura: Preprint
Pubblicazione: 2025
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author Carlton-Jones, Arthur
Suarez, Alonso
Eo, Yun-Suk
Hayes, Ian M.
Saha, Shanta R.
Paglione, Johnpierre
Butch, Nicholas P.
Anlage, Steven M.
author_facet Carlton-Jones, Arthur
Suarez, Alonso
Eo, Yun-Suk
Hayes, Ian M.
Saha, Shanta R.
Paglione, Johnpierre
Butch, Nicholas P.
Anlage, Steven M.
contents The complex surface impedance is a well-established tool to study the super- and normal-fluid responses of superconductors. Fundamental properties of the superconductor, such as the pairing mechanism, Fermi surface, and topological properties, also influence the surface impedance. We explore the microwave surface impedance of spin-triplet UTe$_2$ single crystals as a function of temperature using resonant cavity perturbation measurements employing a novel multi-modal analysis to gain insight into these properties. We determine a composite surface impedance of the crystal for each mode using resonance data combined with the independently measured normal state dc resistivity tensor. The normal state surface impedance reveals the weighting of current flow directions in the crystal of each resonant mode. For UTe$_2$, we find an isotropic $Δλ(T) \sim T^α$ power-law temperature dependence for the magnetic penetration depth for $T\le T_c/3$ with $α< 2$, which is inconsistent with a single pair of point nodes on the Fermi surface under weak scattering. We also find a similar power-law temperature dependence for the low-temperature surface resistance $R_s(T) \sim T^{α_R}$ with $α_R < 2$. We observe a strong anisotropy of the residual microwave loss across these modes, with some modes showing loss below the universal line-nodal value, to those showing substantially more. We compare to predictions for topological Weyl superconductivity in the context of the observed isotropic power-laws, and anisotropy of the residual loss.
format Preprint
id arxiv_https___arxiv_org_abs_2502_07955
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Revealing isotropic abundant low-energy excitations in UTe$_2$ through complex microwave surface impedance
Carlton-Jones, Arthur
Suarez, Alonso
Eo, Yun-Suk
Hayes, Ian M.
Saha, Shanta R.
Paglione, Johnpierre
Butch, Nicholas P.
Anlage, Steven M.
Superconductivity
The complex surface impedance is a well-established tool to study the super- and normal-fluid responses of superconductors. Fundamental properties of the superconductor, such as the pairing mechanism, Fermi surface, and topological properties, also influence the surface impedance. We explore the microwave surface impedance of spin-triplet UTe$_2$ single crystals as a function of temperature using resonant cavity perturbation measurements employing a novel multi-modal analysis to gain insight into these properties. We determine a composite surface impedance of the crystal for each mode using resonance data combined with the independently measured normal state dc resistivity tensor. The normal state surface impedance reveals the weighting of current flow directions in the crystal of each resonant mode. For UTe$_2$, we find an isotropic $Δλ(T) \sim T^α$ power-law temperature dependence for the magnetic penetration depth for $T\le T_c/3$ with $α< 2$, which is inconsistent with a single pair of point nodes on the Fermi surface under weak scattering. We also find a similar power-law temperature dependence for the low-temperature surface resistance $R_s(T) \sim T^{α_R}$ with $α_R < 2$. We observe a strong anisotropy of the residual microwave loss across these modes, with some modes showing loss below the universal line-nodal value, to those showing substantially more. We compare to predictions for topological Weyl superconductivity in the context of the observed isotropic power-laws, and anisotropy of the residual loss.
title Revealing isotropic abundant low-energy excitations in UTe$_2$ through complex microwave surface impedance
topic Superconductivity
url https://arxiv.org/abs/2502.07955