Multigap superconductors provide a platform to confirm rich new physics such as time-reversal symmetry breaking, giant paramagnetic response, and hidden criticality. However, an obstacle hindering the experimental validation of these phenomena lies in the lack of superconductors with three or more gaps and critical temperatures higher than the liquid nitrogen temperature. In this work, we predicted NaB2C2 and Na2B3C3 films with high-temperature superconductivity (beyond 90 K) using the fully anisotropic Migdal-Eliashberg theory. The multigap behaviors of Na–B–C films with three and five atomic layers were analyzed in detail, revealing two typical configurations: three-gap (NaB2C2) and four-gap (Na2B3C3) superconductors. Compared with the NaB2C2 film, the additional gap observed in the Na2B3C3 film originates from the in-plane covalent state of the internal B–C layer. This research offers valuable insights into the evolution of multigap superconductivity in layered B–C films.

中文翻译：

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揭示层状Na-B-C薄膜中多能隙超导的演化：内部B-C层引起的额外能隙


多能隙超导体提供了一个平台来证实丰富的新物理，例如时间反转对称性破缺、巨大的顺磁响应和隐藏的临界性。然而，阻碍这些现象的实验验证的一个障碍在于缺乏具有三个或更多间隙且临界温度高于液氮温度的超导体。在这项工作中，我们利用完全各向异性 Migdal-Eliashberg 理论预测了具有高温超导性（超过 90 K）的 NaB2C2 和 Na2B3C3 薄膜。详细分析了具有三个和五个原子层的Na-B-C薄膜的多能隙行为，揭示了两种典型的结构：三能隙（NaB2C2）和四能隙（Na2B3C3）超导体。与NaB2C2薄膜相比，Na2B3C3薄膜中观察到的额外间隙源于内部B-C层的面内共价态。这项研究为层状 B-C 薄膜中多间隙超导的演化提供了宝贵的见解。