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arXiv 1801.03293cond-mat.supr-concond-mat.str-el
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受空间群对称性保护的非常规超导能隙结构

Unconventional superconducting gap structure protected by space group symmetry

Shuntaro Sumita, Youichi Yanase

摘要:

最近基于空间群对称性的超导能隙分类揭示了点群对称性所没有的非平凡能隙结构。首先,我们回顾了中心对称空间群范围内的安全保护线节点的全面分类。接下来,我们展示了一个额外的约束;非对称系统特有的线节点只出现在原始或正交基心布拉维晶格中。然后,我们列出了超导能隙结构的59个基心空间群的分类表。此外,我们的缺口分类揭示了$j_z$依赖的点节点(缺口开口)出现在3或6倍轴上,这意味着点节点的存在(不存在)取决于布洛赫态角动量$j_z$。我们建议,这种不寻常的间隙结构是实现在重费米子超导体UPt $_3$,使用群论分析和数值计算。计算结果表明,Bloch相位通过位置置换对$j_z$的有效轨道角动量有贡献.我们还讨论了MoS $_2$、SrPtAs、UBe $_{13}$和PrOs $_4$ Sb $_{12}$中的超导能隙结构。

英文摘要:

Recent superconducting gap classifications based on space group symmetry have revealed nontrivial gap structures that were not shown by point group symmetry. First, we review a comprehensive classification of symmetry-protected line nodes within the range of centrosymmetric space groups. Next, we show an additional constraint; line nodes peculiar to nonsymmorphic systems appear only for primitive or orthorhombic base-centered Bravais lattice. Then, we list useful classification tables of 59 primitive or orthorhombic base-centered space groups for the superconducting gap structures. Furthermore, our gap classification reveals the $j_z$-dependent point nodes (gap opening) appearing on a 3- or 6-fold axis, which means that the presence (absence) of point nodes depends on the Bloch-state angular momentum $j_z$. We suggest that this unusual gap structure is realized in a heavy-fermion superconductor UPt$_3$, using a group-theoretical analysis and a numerical calculation. The calculation demonstrates that a Bloch phase contributes to $j_z$ as effective orbital angular momentum by site permutation. We also discuss superconducting gap structures in MoS$_2$, SrPtAs, UBe$_{13}$, and PrOs$_4$Sb$_{12}$.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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