Clean‐Limit 2D Superconductivity in a Thick Exfoliated Kagome Film

Abstract The presence of superconductivity (SC) in low‐dimensional, clean‐limit systems gives rise to abundant exotic quantum properties and provides an ideal platform for advanced device applications. Reduced dimensionality modifies SC and enables topological phases, while clean‐limit systems promise a pathway to utilizing electronic/spintronic devices with enhanced performance. However, achieving clean‐limit 2D SC remains challenging due to the inherent fragility of ultrathin films. Here, clean‐limit 2D SC in a thick exfoliated film of the kagome metal CsV 3 Sb 5 is unambiguously observed. By systematically investigating the transport properties, two lines of direct evidence are identified: 1) a drastic decrease in superfluid stiffness near the superconducting transition; 2) a cusp‐like feature in the angular dependence of the upper critical field ( H c 2 ). Additionally, the observation of in‐plane H c 2 exceeding the Pauli paramagnetic limit confirms the 2D nature of the SC. The clean‐limit nature of the 2D SC establishes CsV 3 Sb 5 as an ideal candidate for fabricating robust superconducting devices with non‐dissipative vortex motion. Furthermore, the interplay between SC and charge‐density‐wave ordering is analyzed, illuminating pathways for identifying systems with similar robust low‐dimensional quantum properties. The findings therefore offer guiding principles for the design of new materials and devices optimized for enhanced superconducting performance and stability.