Twofold van Hove singularity and origin of charge order in topological kagome superconductor CsV3Sb5
Twofold van Hove singularity and origin of charge order in topological kagome superconductor CsV3Sb5
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DOI：
10.1038/s41567-021-01451-5
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发表时间：
2022-01-13
期刊：
影响因子：
19.6
通讯作者：
Comin, Riccardo
中科院分区：
文献类型：
--
作者：
Kang, Mingu;Fang, Shiang;Comin, Riccardo
光谱测量表明CsV_3Sb_5中与kagome晶格相关的能带结构特征对所观察到的强关联相有着重要的贡献.层状钒锑化物AV（3）Sb（5）（A = K，Rb，Cs）是最近发现的一类拓扑kagome金属，具有一系列强关联的电子相，包括电荷有序和超导电性.然而，目前还不清楚戈薇晶格的独特电子结构与观察到的多体现象之间的联系。在这里，我们结合联合收割机角分辨光电子能谱和密度泛函理论，揭示多个kagome派生的货车霍韦奇点（vHS）共存附近的费米能级CsV 3Sb 5和分析其对电子对称性破缺的贡献。vHS的特点是由两个不同的亚晶格风味（p型和m型），这分别源于他们的纯和混合亚晶格字符。这些kagome晶格的双重vHS特征决定了AV（3）Sb（5）系列中出现的配对对称性和非常规基态。我们确定，在CsV 3Sb 5的多重vHS中，d（xz）/d（yz）kagome带的m型vHS和d（xy）/d（x2-y2）kagome带的p型vHS位于非常接近费米能级的位置，为电子对称性破缺奠定了基础。前者的特点是明显的费米面嵌套，而后者表现出更高阶的vHS。我们的工作揭示了kagome衍生的vHS在AV（3）Sb（5）家族中实现的集体现象中的重要作用。
Spectroscopic measurements show how the features of the band structure related to the kagome lattice in CsV3Sb5 contribute to the observed strongly correlated phases.The layered vanadium antimonides AV(3)Sb(5) (A = K, Rb, Cs) are a recently discovered family of topological kagome metals that exhibit a range of strongly correlated electronic phases including charge order and superconductivity. However, it is not yet understood how the distinctive electronic structure of the kagome lattice is linked to the observed many-body phenomena. Here we combine angle-resolved photoemission spectroscopy and density functional theory to reveal multiple kagome-derived van Hove singularities (vHS) coexisting near the Fermi level of CsV3Sb5 and analyse their contribution to electronic symmetry breaking. The vHS are characterized by two distinct sublattice flavours (p-type and m-type), which originate, respectively, from their pure and mixed sublattice characters. These twofold vHS flavours of the kagome lattice critically determine the pairing symmetry and unconventional ground states emerging in the AV(3)Sb(5) series. We establish that, among the multiple vHS in CsV3Sb5, the m-type vHS of the d(xz)/d(yz) kagome band and the p-type vHS of the d(xy)/d(x2-y2) kagome band are located very close to the Fermi level, setting the stage for electronic symmetry breaking. The former band is characterized by pronounced Fermi surface nesting, while the latter exhibits a higher-order vHS. Our work reveals the essential role of kagome-derived vHS for the collective phenomena realized in the AV(3)Sb(5) family.