Anisotropic Superconducting Properties of Kagome Metal CsV<sub>3</sub>Sb<sub>5</sub>
Shunli Ni, Sheng Ma, Yuhang Zhang, Jie Yuan, Haitao Yang, Zouyouwei Lu, Ningning Wang, Jianping Sun, Zhen Zhao, Dong Li, Shaobo Liu, Hua Zhang, Hui Chen, Kui Jin, Jinguang Cheng, Li Yu, Fang Zhou, Xiaoli Dong, Jiangping Hu, Hong-Jun Gao, Zhongxian Zhao
Abstract
We systematically measure the superconducting (SC) and mixed state properties of high-quality CsV 3 Sb 5 single crystals with T c ∼ 3.5 K. We find that the upper critical field H c2 ( T ) exhibits a large anisotropic ratio of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> <mml:mn>2</mml:mn> </mml:mrow> <mml:mrow> <mml:mi>a</mml:mi> <mml:mi>b</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>/</mml:mo> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> <mml:mn>2</mml:mn> </mml:mrow> <mml:mi>c</mml:mi> </mml:msubsup> <mml:mo>∼</mml:mo> <mml:mn>9</mml:mn> </mml:mrow> </mml:math> at zero temperature and fitting its temperature dependence requires a minimum two-band effective model. Moreover, the ratio of the lower critical field, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> <mml:mn>1</mml:mn> </mml:mrow> <mml:mrow> <mml:mi>a</mml:mi> <mml:mi>b</mml:mi> </mml:mrow> </mml:msubsup> <mml:mo>/</mml:mo> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mrow> <mml:mi mathvariant="normal">c</mml:mi> <mml:mn>1</mml:mn> </mml:mrow> <mml:mi>c</mml:mi> </mml:msubsup> </mml:mrow> </mml:math> , 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.