Yu F H, Ma D H, Zhuo W Z, Liu S Q, Wen X K, Lei B, Ying J J, Chen X H
Hefei National Laboratory for Physical Sciences at Microscale and Department of Physics, and CAS Key Laboratory of Strongly-coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, Anhui, China.
CAS Center for Excellence in Quantum Information and Quantum Physics, Hefei, Anhui, China.
Nat Commun. 2021 Jun 10;12(1):3645. doi: 10.1038/s41467-021-23928-w.
Understanding the competition between superconductivity and other ordered states (such as antiferromagnetic or charge-density-wave (CDW) state) is a central issue in condensed matter physics. The recently discovered layered kagome metal AVSb (A = K, Rb, and Cs) provides us a new playground to study the interplay of superconductivity and CDW state by involving nontrivial topology of band structures. Here, we conduct high-pressure electrical transport and magnetic susceptibility measurements to study CsVSb with the highest T of 2.7 K in AVSb family. While the CDW transition is monotonically suppressed by pressure, superconductivity is enhanced with increasing pressure up to P1 ≈ 0.7 GPa, then an unexpected suppression on superconductivity happens until pressure around 1.1 GPa, after that, T is enhanced with increasing pressure again. The CDW is completely suppressed at a critical pressure P2 ≈ 2 GPa together with a maximum T of about 8 K. In contrast to a common dome-like behavior, the pressure-dependent T shows an unexpected double-peak behavior. The unusual suppression of T at P1 is concomitant with the rapidly damping of quantum oscillations, sudden enhancement of the residual resistivity and rapid decrease of magnetoresistance. Our discoveries indicate an unusual competition between superconductivity and CDW state in pressurized kagome lattice.
理解超导与其他有序态（如反铁磁或电荷密度波（CDW）态）之间的竞争是凝聚态物理中的一个核心问题。最近发现的层状 Kagome 金属 AVSb（A = K、Rb 和 Cs）为我们提供了一个新的研究平台，通过涉及能带结构的非平凡拓扑来研究超导与 CDW 态之间的相互作用。在此，我们进行了高压电输运和磁化率测量，以研究 AVSb 家族中 Tc 最高为 2.7 K 的 CsVSb。虽然 CDW 转变被压力单调抑制，但超导性在压力增加到 P1 ≈ 0.7 GPa 之前增强，然后在压力达到约 1.1 GPa 之前对超导性出现意外抑制，之后，Tc 又随压力增加而增强。在临界压力 P2 ≈ 2 GPa 时，CDW 被完全抑制，同时 Tc 达到约 8 K 的最大值。与常见的穹顶状行为不同，压力依赖的 Tc 呈现出意外的双峰行为。在 P1 处 Tc 的异常抑制伴随着量子振荡的迅速衰减、剩余电阻率的突然增加和磁电阻的快速下降。我们的发现表明在加压的 Kagome 晶格中超导与 CDW 态之间存在异常竞争。
