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.

我们系统地测量了T _c ∼ 3.5 K的高质量 CsV ₃ Sb ₅单晶的超导 (SC) 和混合态特性。我们发现上临界场H _c2 ( T )在零温度下表现出较大的各向异性比并拟合其温度依赖性需要一个最小的两波段有效模型。此外，还发现下临界场的比率大于 1，这表明面内能量色散在费米能量附近被强烈重整化。发现H _c1 ( T ) 和 SC 抗磁信号最初在T以下几乎没有变化 _c ~ 3.5 K，然后在冷却到 ~2.8 K 的特征温度时突然增加。此外，我们确定了混合状态下面内角度相关磁阻的两倍各向异性。有趣的是，我们发现，在相同的特征T ∼ 2.8 K 之下，这种双重各向异性的方向显示出特殊的扭曲，角度为 Kagome 几何特征的 60°。我们的研究结果表明，在 Kagome 晶格的复杂环境中出现了一种有趣的超导状态，至少部分是由电子-电子相关性驱动的。