Anisotropic Superconducting Properties of Kagome Metal CsV3Sb5

Abstract

We systematically measure the superconducting (SC) and mixed state properties of high-quality CsV3Sb5 single crystals with T c ∼ 3.5 K. We find that the upper critical field H c2(T) exhibits a large anisotropic ratio of H c 2 a b / H c 2 c ∼ 9 at zero temperature and fitting its temperature dependence requires a minimum two-band effective model. Moreover, the ratio of the lower critical field, H c 1 a b / H c 1 c , is also found to be larger than 1, which indicates that the in-plane energy dispersion is strongly renormalized near Fermi energy. Both H c1(T) and SC diamagnetic signal are found to change little initially below T c ∼ 3.5 K and then to increase abruptly upon cooling to a characteristic temperature of ∼2.8 K. Furthermore, we identify a two-fold anisotropy of in-plane angular-dependent magnetoresistance in the mixed state. Interestingly, we find that, below the same characteristic T ∼ 2.8 K, the orientation of this two-fold anisotropy displays a peculiar twist by an angle of 60° characteristic of the Kagome geometry. Our results suggest an intriguing superconducting state emerging in the complex environment of Kagome lattice, which, at least, is partially driven by electron-electron correlation.