Anisotropic Superconducting Properties of Kagome Metal CsV3Sb5

We systematically measure the superconducting (SC) and mixed state properties of high-quality CsV3Sb5 single crystals with T-c similar to 3.5 K. We find that the upper critical field H-c2(T) exhibits a large anisotropic ratio of H-c2(ab)/H-c2(c)similar to 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-c1(ab)/H-c1(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 similar to 3.5 K and then to increase abruptly upon cooling to a characteristic temperature of similar to 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 similar to 2.8 K, the orientation of this two-fold anisotropy displays a peculiar twist by an angle of 60 degrees 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.

Automated summary

The high-quality CsV3Sb5 single crystals exhibit excellent superconducting and mixed state properties, with a significant anisotropic ratio of Hc2(ab)/Hc2(c) and Hc1(ab)/Hc1(c) larger than 1. The orientation of the two-fold anisotropy in in-plane angular-dependent magnetoresistance displays a unique twist characteristic of the Kagome geometry at a characteristic temperature of around 2.8 K.