非中心对称超导 NbRe 薄膜中退火增强的自旋轨道效应
Annealing-enhanced spin-orbit effects in non-centrosymmetric superconducting NbRe films
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中文总结 AI 辅助
研究热退火对非中心对称超导 NbRe 薄膜超导和正常态磁输运性质的影响，通过 WHH 框架和 Kawabata 模型分析，发现退火增强了自旋轨道介导的量子输运，放大了电子响应，为保护超导态提供关键机制。
中文摘要 AI 辅助
$\text{Nb}_{0.18}\text{Re}_{0.82}$（NbRe）是一种非中心对称超导体，块状形式的转变温度$T_\mathrm{c}$可达 9K。块状和单晶 NbRe 呈现多能隙超导特征，而薄膜因结构无序和微晶尺寸减小通常表现为单能隙超导态。本文研究了热退火对 NbRe 薄膜超导和正常态磁输运性质的影响。在微观 Werthamer--Helfand--Hohenberg（WHH）框架内分析上临界场$B_{\mathrm{c2}}(T)$的温度依赖性，用三维 Kawabata 弱局域化/弱反局域化模型描述正常态磁导率。退火使电子响应发生显著变化，正常态呈现强的弱反局域化行为，上临界场超过传统轨道限制场和泡利顺磁极限。微观分析表明相对自旋轨道散射强度有强烈的内在增加，退火薄膜的自旋轨道与退相场比显著增强。这些发现提供了直接、独立的证据，证明 NbRe 微观结构的热改性成功放大了自旋轨道介导的量子输运，这是保护非中心对称超导态免受顺磁对破坏的关键机制，超越了传统理论界限。
英文摘要
$\text{Nb}_{0.18}\text{Re}_{0.82}$ (NbRe) is a non-centrosymmetric superconductor with a transition temperature $T_\mathrm{c}$ reaching $9\text{ K}$ in bulk form. While bulk and single-crystalline NbRe exhibit signatures of multigap superconductivity, thin films generally display a single-gap superconducting state due to structural disorder and reduced crystallite dimensions. Here, we investigate the impact of thermal annealing on the superconducting and normal-state magnetotransport properties of NbRe films. The temperature dependence of the upper critical field, $B_{\mathrm{c2}}(T)$, is analyzed within the microscopic Werthamer--Helfand--Hohenberg (WHH) framework, while the normal-state magnetoconductivity is described using the three-dimensional Kawabata weak-localization/weak-anti-localization model. Annealing drives a pronounced change in the electronic response, manifested by a strong weak anti-localization behavior in the normal state and an upper critical field that surpasses both the conventional orbital-limiting field and the Pauli paramagnetic limit. The microscopic analysis reveals a strong intrinsic increase in the relative spin--orbit scattering strength, with the annealed film showing a significantly enhanced spin--orbit-to-dephasing field ratio. These findings provide direct, independent evidence that thermal modification of the NbRe microstructure successfully amplifies spin--orbit-mediated quantum transport, which acts as the key mechanism protecting the non-centrosymmetric superconducting state against paramagnetic pair-breaking well beyond conventional theoretical boundaries.
