标题： 自旋三重态超导性在外尔节线半金属中 显示英文标题

标题： Spin-triplet superconductivity in Weyl nodal-line semimetals

摘要： 拓扑半金属是具有对称性保护的无质量体激发的三维材料。 作为特殊情况，外尔节线半金属在没有倒置对称性或时间反演对称性被破坏的材料中实现，并具有体节线。 111族材料，LaNiSi、LaPtSi和LaPtGe（均缺乏倒置对称性），属于此类。 在这里，通过结合μ子自旋旋转和弛豫与热力学测量，我们发现这些材料表现出完全间隙的超导基态，而在超导转变时自发地打破时间反演对称性。 由于时间反演对称性对于保护正常态的拓扑结构至关重要，进入超导态时其破坏应显著导致拓扑相变。 通过开发一个正常态能带结构的最小模型并假设纯自旋三重态配对，我们表明该族的超导特性可以被准确描述。 我们的结果表明，这里报道的111族材料为研究外尔节线费米子的奇特性质与非常规超导性之间的丰富相互作用提供了一个理想的测试平台。 显示英文摘要

摘要： Topological semimetals are three dimensional materials with symmetry-protected massless bulk excitations. As a special case, Weyl nodal-line semimetals are realized in materials either having no inversion or broken time-reversal symmetry and feature bulk nodal lines. The 111-family of materials, LaNiSi, LaPtSi and LaPtGe (all lacking inversion symmetry), belong to this class. Here, by combining muon-spin rotation and relaxation with thermodynamic measurements, we find that these materials exhibit a fully-gapped superconducting ground state, while spontaneously breaking time-reversal symmetry at the superconducting transition. Since time-reversal symmetry is essential for protecting the normal-state topology, its breaking upon entering the superconducting state should remarkably result in a topological phase transition. By developing a minimal model for the normal-state band structure and assuming a purely spin-triplet pairing, we show that the superconducting properties across the family can be described accurately. Our results demonstrate that the 111-family reported here provides an ideal test-bed for investigating the rich interplay between the exotic properties of Weyl nodal-line fermions and unconventional superconductivity.