标题： 无间隙超导性来自2H-NbSe2-xSx中的极稀磁杂质 显示英文标题

标题： Gapless superconductivity from extremely dilute magnetic disorder in 2H-NbSe2-xSx

摘要： 大多数超导材料在费米能级处的态密度趋于零，安德森定理指出超导能隙对非磁性无序具有鲁棒性。尽管稀疏的磁性杂质会导致间隙内状态的局域化，但这些状态通常与材料的整体超导性质无关。然而，许多实验显示，在磁性杂质数量似乎可以忽略的系统中，费米能级处存在有限的态密度。在这里，我们使用扫描隧道显微镜和自洽的博戈留波夫-德热纳计算，发现2H-NbSe2-xSx在非常低的磁性杂质浓度下出现了无能隙的超导性。此外，我们的密度泛函理论计算和间隙内准粒子干涉测量表明，Se-S取代显著改变了能带结构。这种改变促进了嵌套，并决定了x>0时的间隙内散射，这与纯2H-NbSe2中的主要电荷密度波相互作用形成鲜明对比。我们的发现揭示了超导体对无序的不寻常响应，并强调了在理解超导体对极低浓度磁性杂质的响应时，纳入材料特定的能带结构的重要性。 显示英文摘要

摘要： Most superconducting materials exhibit a vanishing density of states at the Fermi level and Anderson's theorem posits that the superconducting gap is robust against nonmagnetic disorder. Although dilute magnetic impurities lead to localized in-gap states, these states typically have no bearing on the material's bulk superconducting properties. However, numerous experiments reveal a finite density of states at the Fermi level in systems with an apparently negligible number of magnetic impurities. Here, using scanning tunneling microscopy and self-consistent Bogoliubov-de Gennes calculations, we find that gapless superconductivity emerges in 2H-NbSe2-xSx at remarkably low magnetic impurity concentrations. Furthermore, our density functional theory calculations and in-gap quasiparticle interference measurements demonstrate that the Se-S substitution significantly modifies the band structure. This modification favours nesting and dictates the in-gap scattering for x>0, in stark contrast to the dominant charge density wave interactions in pure 2H-NbSe2. Our findings reveal an unusual superconducting response to disorder and highlight the importance of incorporating material-specific band structures in the understanding of a superconductor's response to even very low concentrations of magnetic impurities.