Coexistence of Quasi-two-dimensional Superconductivity and Tunable Kondo Lattice in a van der Waals Superconductor

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-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.

Modulating Charge-Density Wave Order and Superconductivity from Two Alternative Stacked Monolayers in a Bulk 4Hb-TaSe2 Heterostructure via Pressure

“…Recently, the emerging natural bulk TMD VDWHs that share configurations similar to those of 2D VDWHs are ideal systems suitable for such studies. They are alternately stacked with octahedral ( T ) layers with CDW order and trigonal-prismatic ( H ) layers with superconductivity and different CDW orders. − Pressure is a clean, continuous, and reversible way to regulate the interlayer coupling by changing the interlayer distance without introducing any chemical impurities into VDWHs. , Pressure has also been broadly applied in bulk TMD systems to tune the electronic properties associated with the CDW states and superconductivity. − …”

Comparative coherence between layered and traditional semiconductors: unique opportunities for heterogeneous integration

“…The superconductivity of 2D materials, such as the much-publicized magic-angle graphene [167], has aroused great interest in the field of physics. Shen et al demonstrated in their research on 4Hb-TaS 2 that the quasi 2D superconductivity in the 1H layer coexists with the Kondo resonance in the 1T layer, and the intensity of the Kondo resonance peak can be modulated by adjusting its relative position to the Fermi level [168].…”

Charge transfer and spin-valley locking in 4Hb-TaS2

“…The role of these new bands in superconductivity is not clear. It has been suggested that Kondo physics seen in 4Hb 22,23 and in 1T/1H bilayers 13 could be related to these narrow bands.…”