Nodeless superconductivity in the kagome metal CsV3Sb5

The recently discovered kagome metal series AV(3)Sb(5) (A=K, Rb, Cs) exhibits topologically nontrivial band structures, chiral charge order and superconductivity, presenting a unique platform for realizing exotic electronic states. The nature of the superconducting state and the corresponding pairing symmetry are key questions that demand experimental clarification. Here, using a technique based on the tunneling diode oscillator, the magnetic penetration depth Delta lambda(T) of CsV3Sb5 was measured down to 0.07 K. A clear exponential behavior in Delta lambda(T) with marked deviations from a T or T-2 temperature dependence was observed at low temperatures, indicating an absence of nodal quasiparticles. Temperature dependence of the superfluid density and electronic specific heat can be described by two-gap s-wave superconductivity, consistent with the presence of multiple Fermi surfaces in CsV3Sb5. These results evidence nodeless superconductivity in CsV3Sb5 under ambient pressure, and constrain the allowed pairing symmetry.

Automated summary

CsV3Sb5 exhibits nodeless superconductivity consistent with two-gap s-wave superconductivity description, and is confirmed under multiple Fermi surfaces.