2026/07/21 by Zahra Makhdoumi Kakhaki, Yuriy Yerin, Francesco Avitabile +5
#cond-mat.supr-con
Nb0.18Re0.82 (NbRe) is a non-centrosymmetric superconductor with a transition temperature Tc reaching 9 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, Bc2(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.