Anisotropic Superconducting Properties of Kagome Metal CsV3Sb5 Supported by the National Natural Science Foundation of China (Grant Nos. 11834016, 11888101, 12061131005, 51771224 and 61888102), the National Key Research and Development Projects of China (Grant Nos. 2017YFA0303003 and 2018YFA0305800), the Key Research Program and Strategic Priority Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant Nos. QYZDY-SSW-SLH001, XDB33010200

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 at zero temperature and fitting its temperature dependence requires a minimum two-band effective model. Moreover, the ratio of the lower critical field, , 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.