Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor
Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor
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范德华超导体中准二维超导性和可调谐近藤晶格的共存
DOI：
10.1088/0256-307x/39/7/077401
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发表时间：
2022-05
期刊：
影响因子：
--
通讯作者：
Shichao Yan
中科院分区：
文献类型：
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作者：
Shiwei Shen;Tian Qin;Jingjing Gao;Chenhaoping Wen;Jinghui Wang;Wei Wang;Jun Li;Xuan Luo;Wenjian Lu;Yuping Sun;Shichao Yan
近藤晶格在超导范德华材料中的实现，不仅为通过电门控或插层调整近藤晶格行为提供了独特的机会，而且有助于进一步理解重费米子的超导性。本文报道了一种超导化合物（4Hb-TaS2）的低温矢量磁场扫描隧道显微镜和光谱研究，该化合物具有1T-TaS2和1H-TaS2层交替堆叠。我们观察到h - tas2层的准二维超导性，其对面内和面外磁场的各向异性响应。在1T-TaS2层，我们检测到近藤共振峰，这是由近藤筛选大卫之星团簇中的未配对电子产生的。我们还发现Kondo共振峰的强度对其与费米能级的相对位置很敏感，并且通过在1T-TaS2表面蒸发Pb原子使其进一步向费米能级移动可以显著增强。我们的研究结果不仅对充分理解4Hb-TaS2的电子特性具有重要意义，而且为在超导范德华材料中创建可调谐近藤晶格铺平了道路。
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-TaS2) with alternate stacking of 1T-TaS2 and 1H-TaS2 layers. We observe the quasi-two-dimensional superconductivity in the 1H-TaS2 layer with anisotropic response to the in-plane and out-of-plane magnetic fields. In the 1T-TaS2 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 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's further shifted towards the Fermi level by evaporating Pb atoms onto the 1T-TaS2 surface. Our results are not only important for fully understanding the electronic properties of 4Hb-TaS2, but also pave the way for creating tunable Kondo lattice in the superconducting van der Waals materials.