2024/08/15 by Sun, Fei, Salinas, Andrea Capa, Wilson, Stephen D. +1 · 1 citation
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Strongly Correlated Electrons (cond-mat.str-el) #Superconductivity (cond-mat.supr-con)
paper · doi:10.48550/arxiv.2408.08117
We report the observation of two-dimensional superconductivity (2D SC) in exfoliated kagome metal CsV3Sb5 with a thickness far thicker than the atomic limit. By examining the critical current and upper critical magnetic fields (Hc2) of 40-60 nm thick films in the superconducting state, we identify a pronounced Berezinskii-Kosterlitz-Thouless (BKT) transition behavior, i.e. a drastic decrease of the superfluid stiffness near the transition, and a cusp-like feature of the angular dependent Hc2, both of which serve as direct evidence of 2D SC. In addition, an exceeding of the Pauli paramagnetic limit of the in-plane Hc2 is consistent with the 2D SC nature. The observed 2D SC occurs in thick films with the highest superconducting transition temperature Tc and the lowest charge density wave transition temperature T_\rm CDW, which suggests that the charge density wave states are interrelated with the superconducting states. Our findings impose constraints in understanding the enhancement of SC in kagome superconductors, and illuminate pathways for achieving novel 2D superconducting states in more stable and much thicker systems.