发表机构
Institute of Experimental Physics, Slovak Academy of Sciences; P. J. Šafárik University; Centre of Excellence ENSEMBLE3 Sp. z o. o.; AGH University of Krakow; Gdansk University of Technology（斯洛伐克科学院实验物理研究所; 帕夫约夫·沙法里克大学; ENSEMBLE3卓越中心有限公司; 克拉科夫AGH科技大学; 格但斯克理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
ScAu$_2$Al是Tc接近5K的Heusler超导体，通过量热和输运测量结合Eliashberg计算，证实其为强耦合多能隙超导体，比热跳变和耦合常数均高于BCS弱耦合值，电阻上临界场增强归因于晶界无序区域超导。
AI 中文摘要
ScAu$_2$Al是Heusler超导体中报道的最高转变温度Tc接近5K的超导体。这里，我们将高分辨率交流量热法和电输运测量与基于第一性原理的Eliashberg计算相结合。大的比热跳变${\Delta}C/{\gamma_nT_c} =$ 2.2，远高于弱耦合BCS值1.43，加上电子-声子耦合常数${\lambda} = $1.1，确立了ScAu2Al为强耦合超导体。电子比热由双能隙{\alpha}模型描述更好，其中$2{\Delta}_S/k_BT_c = $ 4.1和$2{\Delta}_L/k_BT_c = $ 4.8，优于单能隙模型。热力学上临界场遵循常规的WHH类温度依赖性，$B_{c2}(0) = 0.18$ T，而电阻测量的临界场达到约三倍大的值，并表现出显著的正曲率。我们将增强的电阻场尺度归因于无序晶界和界面区域的超导电性。实验结果得到了在Eliashberg形式下使用第一性原理计算获得的费米面和电子-声子参数对热容和上临界场的计算支持。
英文摘要
ScAu$_2$Al 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
Comments7 pages with 7 figures plus Supplemental Material
