论文标题
多胎费金属中的拓扑超导性
Topological Superconductivity in Multifold Fermion Metals
论文作者
论文摘要
最近,在ALPT [ARXIV:1812.03310]和XSI(X = RH,CO)[ARXIV:1812.04466] [ARXIV:1901.033333333333333358]中,以实验中发现了具有多胎退化性和非平凡的Chern数字的多胎退化性和费米表面的多胎fermions。在这项工作中,我们在很大程度上可以通过指出几个良好研究的非中心超对象的多胎材料家族的家族确实是多胎费金属。重要的是,在先前的研究中忽略了它们的正常状态拓扑特性,在超导性能中起着重要作用。以李$ _2 $ pd $ _3 $ b和li $ _2 $ pt $ _3 $ b为例,我们发现了大量非常规的退化点,例如双旋转1,spin-3/2,Weyl和双Weyl拓扑和双Weyl拓扑结构杂交点附近的Fermi Energy附近的Fermi Energy,这在Fermi Surface上导致了Fermi Chern数量。发现了li $ _2 $ pd $ _3 $ b的长费米弧状态,源自非平凡的乐队拓扑。重要的是,已经从实验上证明了李$ _2 $ pd $ _3 $ b和li $ _2 $ pt $ _3 $ b分别完全散布和无间隙的超导体。通过分析可能的配对对称性,我们建议Li $ _2 $ PD $ _3 $ b可以是DIIII类拓扑超导体,即使Majorana Surface States状态,即使以Li $ _2 $ _2 $ PD $ _3 $ _3 $ b的旋转耦合也可以忽略不计。有趣的是,Li $ _2 $ pt $ _3 $ b,无间隙,很可能是具有无散表面Majorana模式的节点拓扑超导体。 We further identified that several noncentrosymmetric superconductors, such as Mo$_3$Al$_2$C, PdBiSe, Y$_2$C$_3$ and La$_2$C$_3$, are multifold fermion superconductors whose normal state topological properties have been ignored in previous experimental and theoretical studies.
Recently, multifold fermions characterized by band crossings with multifold degeneracy and Fermi surfaces with nontrivial Chern numbers have been discovered experimentally in AlPt[arXiv:1812.03310] and XSi(X=Rh,Co)[arXiv:1812.04466][arXiv:1901.03358][arXiv:1809.01312]. In this work, we largely expand the family of multifold fermion materials by pointing out that several well-studied noncentrosymmetric superconductors are indeed multifold fermion metals. Importantly, their normal state topological properties, which have been ignored in previous studies, play an important role in the superconducting properties. Taking Li$_2$Pd$_3$B and Li$_2$Pt$_3$B as examples, we found a large number of unconventional degenerate points, such as double spin-1, spin-3/2, Weyl and double Weyl topological band crossing points near the Fermi energy, which result in finite Chern numbers on Fermi surfaces. Long Fermi arc states in Li$_2$Pd$_3$B, originating from the nontrivial band topology were found. Importantly, it has been shown experimentally that Li$_2$Pd$_3$B and Li$_2$Pt$_3$B are fully gapped and gapless superconductors, respectively. By analyzing the possible pairing symmetries, we suggest that Li$_2$Pd$_3$B can be a DIII class topological superconductor with Majorana surface states, even though the spin-orbit coupling in Li$_2$Pd$_3$B is negligible. Interestingly, Li$_2$Pt$_3$B, being gapless, is likely to be a nodal topological superconductor with dispersionless surface Majorana modes. We further identified that several noncentrosymmetric superconductors, such as Mo$_3$Al$_2$C, PdBiSe, Y$_2$C$_3$ and La$_2$C$_3$, are multifold fermion superconductors whose normal state topological properties have been ignored in previous experimental and theoretical studies.