标题： 可能存在于 Kagome 超导体中的受挫超导性 显示英文标题

标题： The possible frustrated superconductivity in the kagome superconductors

摘要： 几何阻挫长期以来一直是凝聚态物理学中的一个研究热点。尽管几何阻挫传统上主要集中在磁性系统上，但当超导相互作用与晶体对称性相冲突时可能出现的“阻挫超导性”却很少受到关注。最近发现的kagome超导体由于其受阻的晶格结构和三个子晶格之间的干涉效应可以促进阻挫超导相互作用，因此为研究这一点提供了特殊的机会。 在这里，我们提出了一种支持阻挫超导态的理论，该理论基于轨道上的$s$波超导配对，结合最近邻配对跃迁以及独特的几何阻挫晶格结构。在这种状态下，超导配对相位的相互$2\pi/3$差异导致了振幅的六重调制，并且破坏了时间反演对称性，在超导配对相位随$4\pi$变化的情况下，随着绕费米面移动而变化，它对杂质具有免疫力，没有由杂质引起的能隙状态，并在低于$T_{c}$时产生显著的核自旋-晶格弛豫率的Hebel-Slichter峰。值得注意的是，该理论还揭示了一种从阻挫超导态到各向同性$s$波超导态的无节点过渡的无序诱导超导配对转变，恢复并解释了实验中发现的行为。 这项研究不仅为调解关于超导配对对称性的发散或看似矛盾的实验结果提供了一个有希望的提案，也可能为推进对阻挫超导态的研究铺平道路。 显示英文摘要

摘要： Geometric frustration has long been a subject of enduring interest in condensed matter physics. While geometric frustration traditionally focuses on magnetic systems, little attention is paid to the "frustrated superconductivity" which could arise when the superconducting interaction conflicts with the crystal symmetry. The recently discovered kagome superconductors provide a particular opportunity for studying this due to the fact that the frustrated lattice structure and the interference effect between the three sublattices can facilitate the frustrated superconducting interaction. Here, we propose a theory that supports the frustrated superconducting state, derived from the on-site $s$-wave superconducting pairing in conjunction with the nearest-neighbor pairings hoping and the unique geometrical frustrated lattice structure. In this state, whereas the mutual $2\pi/3$ difference of the superconducting pairing phase causes the six-fold modulation of the amplitude and breaks the time-reversal symmetry with $4\pi$ phase changes of the superconducting pairing as one following it around the Fermi surface, it is immune to the impurities without the impurity-induced in-gap states and produces the pronounced Hebel-Slichter peak of the nuclear spin-lattice relaxation rate below $T_{c}$. Notably, the theory also reveals a disorder-induced superconducting pairing transition from the frustrated superconducting state to an isotropic $s$-wave superconducting state without traversing the nodal points, recovering and explaining the behavior found in experiment. This study not only serves as a promising proposal to mediate the divergent or seemingly contradictory experimental outcomes regarding superconducting pairing symmetry, but may also pave the way for advancing investigations into the frustrated superconducting state.