Strong-coupling multigap superconductivity in the Heusler compound ScAu2Al
Abstract
ScAu2Al is the Heusler superconductor with the highest reported transition temperature, Tc, close to 5 K. Here, we combine high-resolution ac calorimetry and electrical-transport measurements with first-principles-based Eliashberg calculations. The large specific-heat jump, ΔC/γnTc = 2.2, well above the weak-coupling BCS value of 1.43, together with an electron-phonon coupling constant $λ = $1.1, establishes ScAu2Al as a strong-coupling superconductor. The electronic specific heat is described better by a two-gap α model, with $2Δ_S/k_BT_c = $ 4.1 and $2Δ_L/k_BT_c = $ 4.8, than by a single-gap model. The thermodynamic upper critical field follows a conventional WHH-like temperature dependence with Bc2(0) = 0.18 T, whereas the resistively determined critical field reaches values about three times larger and exhibits a pronounced positive curvature. We attribute the enhanced resistive field scale to superconductivity in disordered grain-boundary and interfacial regions. The experimental results are supported by calculations of the heat capacity and upper critical field within the Eliashberg formalism using Fermi-surface and electron-phonon parameters obtained from first-principles calculations
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BibTeX
@misc{kacmarcik2026strongcoupling,
title = {{Strong-coupling multigap superconductivity in the Heusler compound ScAu$_2$Al}},
author = {Jozef Kačmarčík and Zuzana Pribulová and Yevhen Petrenko and Gabriel Kuderowicz and Paweł Wójcik and Michał J. Winiarski and Szymon M. Królak and Filip Košuth and Pavol Szabó and Tomasz Klimczuk and Bartlomiej Wiendlocha and Peter Samuely},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.21845},
eprint = {2609.21845},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.21845},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Strong-coupling multigap superconductivity in the Heusler compound ScAu_2Al
AU - Jozef Kačmarčík
AU - Zuzana Pribulová
AU - Yevhen Petrenko
AU - Gabriel Kuderowicz
AU - Paweł Wójcik
AU - Michał J. Winiarski
AU - Szymon M. Królak
AU - Filip Košuth
AU - Pavol Szabó
AU - Tomasz Klimczuk
AU - Bartlomiej Wiendlocha
AU - Peter Samuely
PY - 2026
DA - 2026/09/18
PB - arXiv
DO - 10.48550/arxiv.2609.21845
UR - https://arxiv.org/abs/2609.21845
AB - ScAu_2Al is the Heusler superconductor with the highest reported transition temperature, Tc, close to 5 K. Here, we combine high-resolution ac calorimetry and electrical-transport measurements with first-principles-based Eliashberg calculations. The large specific-heat jump, ΔC/γ_nT_c = 2.2, well above the weak-coupling BCS value of 1.43, together with an electron-phonon coupling constant $λ = $1.1, establishes ScAu2Al as a strong-coupling superconductor. The electronic specific heat is described better by a two-gap α model, with $2Δ_S/k_BT_c = $ 4.1 and $2Δ_L/k_BT_c = $ 4.8, than by a single-gap model. The thermodynamic upper critical field follows a conventional WHH-like temperature dependence with B_c2(0) = 0.18 T, whereas the resistively determined critical field reaches values about three times larger and exhibits a pronounced positive curvature. We attribute the enhanced resistive field scale to superconductivity in disordered grain-boundary and interfacial regions. The experimental results are supported by calculations of the heat capacity and upper critical field within the Eliashberg formalism using Fermi-surface and electron-phonon parameters obtained from first-principles calculations
ER -