Commensurate-to-incommensurate transition of charge-density-wave order and a possible quantum critical point in pressurized kagome metal CsV3Sb5
X. Y. Feng, Zhongxian Zhao, J. L. Luo, Jiyong Yang, A. F. Fang, Haitao Yang, H. J. Gao, Rui Zhou, Guo‐qing Zheng
Abstract
Abstract Clarifying the interplay between charge-density waves (CDWs) and superconductivity is important in the kagome metal CsV 3 Sb 5 , and pressure ( P ) can play a crucial role. Here, we present 121/123 Sb nuclear quadrupole resonance (NQR) measurements under hydrostatic pressures up to 2.43 GPa in CsV 3 Sb 5 single crystals. We demonstrate that the CDW gradually changes from a commensurate modulation with a star-of-David (SoD) pattern to an incommensurate one with a superimposed SoD and Tri-hexagonal (TrH) pattern stacking along the c -axis. Moreover, the linewidth δ ν of 121/123 Sb-NQR spectra increases with cooling down to T CDW , indicating the appearance of a short-range CDW order due to CDW fluctuations pinned by quenched disorders. The δ ν shows a Curie–Weiss temperature dependence and tends to diverge at P c ~ 1.9 GPa, suggesting that a CDW quantum critical point (QCP) exists at P c where T c shows the maximum. For P > P c , spin fluctuations are enhanced when the CDW is suppressed. Our results suggest that the maximal T c at P c ~ 1.9 GPa is related to the CDW QCP, and the presence of spin fluctuations prevents the T c from a rapid decrease otherwise, after the CDW is completely suppressed.