论文标题
Kagome超导体CS（V1-XNBX）3SB5中TC增强的Fermiology和起源
Fermiology and Origin of Tc Enhancement in a Kagome Superconductor Cs(V1-xNbx)3Sb5
论文作者
论文摘要
kagome金属AV3SB5（A = K，RB和CS）表现出与电荷密度波（CDW）共存的特征性超导基态，而超导性和CDW的机制尚未澄清。在这里，我们报告了CS（V1-XNBX）3SB5的系统ARPES研究，这是NB含量X的函数，其中Isovalent NB取代会导致超导过渡温度（TC）的增强和CDW温度降低（TCDW）。我们发现，NB替代将SB衍生的电子带向下移动SB衍生的电子带，并同时将V衍生的带围绕M点移动，以向上移动，以将鞍点（SP）从费米级提升，从而降低了CDW-GAP幅度和TCDW。这表明状态稳定CDW的SP密度的主要作用。目前的结果还表明，NB取代的超导性增强是由SB衍生的电子口袋的扩展与费米水平上V衍生状态的恢复之间的合作引起的。
Kagome metals AV3Sb5 (A = K, Rb, and Cs) exhibit a characteristic superconducting ground state coexisting with charge-density wave (CDW), whereas the mechanisms of the superconductivity and CDW have yet to be clarified. Here we report a systematic ARPES study of Cs(V1-xNbx)3Sb5 as a function of Nb content x, where isovalent Nb substitution causes an enhancement of superconducting transition temperature (Tc) and the reduction of CDW temperature (TCDW). We found that the Nb substitution shifts the Sb-derived electron band at the Gamma point downward and simultaneously moves the V-derived band around the M point upward to lift up the saddle point (SP) away from the Fermi level, leading to the reduction of CDW-gap magnitude and TCDW. This indicates a primary role of the SP density of states to stabilize CDW. The present result also suggests that the enhancement of superconductivity by Nb substitution is caused by the cooperation between the expansion of the Sb-derived electron pocket and the recovery of the V-derived density of states at the Fermi level.
