Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor
Shiwei Shen1, Tian Qin1, Jingjing Gao2,3, Chenhaoping Wen1, Jinghui Wang1,4, Wei Wang2,3, Jun Li1,4, Xuan Luo2, Wenjian Lu2, Yuping Sun2,5,6*, and Shichao Yan1,4*
1School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China 2Key Laboratory of Materials Physics, Institute of Solid State Physics, HFIPS, Chinese Academy of Sciences, Hefei 230031, China 3University of Science and Technology of China, Hefei 230026, China 4ShanghaiTech Laboratory for Topological Physics, ShanghaiTech University, Shanghai 201210, China 5High Magnetic Field Laboratory, HFIPS, Chinese Academy of Sciences, Hefei 230031, China 6Collaborative Innovation Centre of Advanced Microstructures, Nanjing University, Nanjing 210093, China
Abstract：Realization of Kondo lattice in superconducting van der Waals materials not only provides a unique opportunity for tuning the Kondo lattice behavior by electrical gating or intercalation, but also is helpful for further understanding the heavy fermion superconductivity. Here we report a low-temperature and vector-magnetic-field scanning tunneling microscopy and spectroscopy study on a superconducting compound (4Hb-TaS$_{2})$ with alternate stacking of 1T-TaS$_{2}$ and 1H-TaS$_{2}$ layers. We observe the quasi-two-dimensional superconductivity in the 1H-TaS$_{2}$ layer with anisotropic response to the in-plane and out-of-plane magnetic fields. In the 1T-TaS$_{2}$ layer, we detect the Kondo resonance peak that results from the Kondo screening of the unpaired electrons in the Star-of-David clusters. We also find that the intensity of the Kondo resonance peak is sensitive to its relative position with the Fermi level, and it can be significantly enhanced when it is further shifted towards the Fermi level by evaporating Pb atoms onto the 1T-TaS$_{2}$ surface. Our results not only are important for fully understanding the electronic properties of 4Hb-TaS$_{2}$, but also pave the way for creating tunable Kondo lattice in the superconducting van der Waals materials.
2022, Vol. 39 
