Microscopic evidence for anisotropic multigap superconductivity in the CsV 3 Sb 5 kagome superconductor

The recently discovered kagome superconductor CsV 3 Sb 5 ( T c ≃ 2.5 K) has been found to host charge order as well as a non-trivial band topology, encompassing multiple Dirac points and probable surface states. Such a complex and phenomenologically rich system is, therefore, an ideal playground for observing unusual electronic phases. Here, we report anisotropic superconducting properties of CsV 3 Sb 5 by means of transverse-field muon spin rotation ( μ SR) experiments. The fits of temperature dependences of in-plane and out-of-plane components of the magnetic penetration depth suggest that the superconducting order parameter may have a two-gap ( s + s )-wave symmetry. The multiband nature of superconductivity could be further supported by the different temperature dependences of the anisotropic magnetic penetration depth γ λ ( T ) and upper critical field γ_B_c2(T) . The relaxation rates obtained from zero field μ SR experiments do not show noticeable change across the superconducting transition, indicating that superconductivity does not break time reversal symmetry.