[Yeahan Sur, Kwang-Tak Kim & Prof. Kee Hoon Kim] Optimized superconductivity in the vicinity of a nematic quantum critical point in the kagome superconductor Cs(V1-xTix)3Sb5
CsV3Sb5 exhibits superconductivity at Tc=3.2 K after undergoing intriguing two high-temperature transitions: charge density wave order at ~98 K and electronic nematic order at Tnem~35 K. Here, we investigate nematic susceptibility in single crystals of Cs(V1-xTix)3Sb5 (x=0.00-0.06) where double-dome-shaped superconducting phase diagram is realized. The nematic susceptibility typically exhibits the Curie‒Weiss behavior above Tnem, which is monotonically decreased with x. Moreover, the Curie‒Weiss temperature is systematically suppressed from ~30 K for x=0 to ~4 K for x=0.0075, resulting in a sign change at x=~0.009. Furthermore, the Curie constant reaches a maximum at x=0.01, suggesting drastically enhanced nematic susceptibility near a putative nematic quantum critical point (NQCP) at x=~0.009. Strikingly, Tc is enhanced up to ~4.1 K with full Meissner shielding realized at x=~0.0075-0.01, forming the first superconducting dome near the NQCP. Our findings directly point to a vital role of nematic fluctuations in enhancing the superconducting properties of Cs(V1-xTix)3Sb5.
Nat. Commun. 14, 3899 (2023)
doi: 10.1038/s41467-023-39495-1
doi: 10.1038/s41467-023-39495-1