Symmetry-Based Approach to Superconducting Nodes: Unification of Compatibility Conditions and Gapless Point Classifications
Symmetry-Based Approach to Superconducting Nodes: Unification of Compatibility Conditions and Gapless Point Classifications
复制标题
DOI：
10.1103/physrevx.12.011021
复制
发表时间：
2021-02
影响因子：
12.5
通讯作者：
Seishiro Ono;Ken Shiozaki
中科院分区：
文献类型：
--
作者：
Seishiro Ono;Ken Shiozaki
确定超导带隙的对称性是理解非常规超导机制的一个中心问题。虽然通常很难完全实现上述目标，但超导节点的存在，作为非常规超导的少数重要实验特征之一，在探索非常规超导的可能性方面起着至关重要的作用。超导节点和拓扑结构之间的相互作用已经被积极研究，在过去的十年中，深入的研究已经揭示了各种有趣的节点的范围内的开创性工作，超导序参数分类的基础上的点群。然而，对于任意对称设置的超导节点的系统和统一的描述仍然是难以捉摸的。在本文中，我们开发了一个系统的框架，全面分类超导节点钉扎到任何线在动量空间。虽然大多数以前的研究都是基于同伦理论，但我们的理论是基于带拓扑的对称性分析，这使得能够系统地诊断所有非磁性和磁性空间群中的节点。此外，我们的框架可以很容易地提供一个非常有效的计划来检测节点在一个给定的超导体通过使用密度泛函理论和假设的对称性的库珀对（称为配对对称性），这可以减少候选人的配对对称性。我们通过时间反演破碎和非中心对称超导体CaPtAs证实了我们的方法的力量。我们的工作建立了一个统一的理论来理解超导节点，并有助于确定超导材料结合实验观察的差距。
Determination of the symmetry property of superconducting gaps has been a central issue in studies to understand the mechanisms of unconventional superconductivity. Although it is often difficult to completely achieve the aforementioned goal, the existence of superconducting nodes, one of the few important experimental signatures of unconventional superconductivity, plays a vital role in exploring the possibility of unconventional superconductivity. The interplay between superconducting nodes and topology has been actively investigated, and intensive research in the past decade has revealed various intriguing nodes out of the scope of the pioneering work to classify superconducting order parameters based on the point groups. However, a systematic and unified description of superconducting nodes for arbitrary symmetry settings is still elusive. In this paper, we develop a systematic framework to comprehensively classify superconducting nodes pinned to any line in momentum space. While most previous studies have been based on the homotopy theory, our theory is on the basis of the symmetry-based analysis of band topology, which enables systematic diagnoses of nodes in all nonmagnetic and magnetic space groups. Furthermore, our framework can readily provide a highly effective scheme to detect nodes in a given superconductor by using density functional theory and assuming symmetry properties of Cooper pairs (called pairing symmetries), which can reduce candidates of pairing symmetries. We substantiate the power of our method through the time-reversal broken and noncentrosymmetric superconductor CaPtAs. Our work establishes a unified theory for understanding superconducting nodes and facilitates determining superconducting gaps in materials combined with experimental observations.