Kelvin Probe Force Microscopy Study on Chiral Superconductor 4Hb-TaS₂

Van der Waals material is a new kind of thin material, which is connected by several thin layers of covalent bonds of the same or different atoms through weak van der Waals interaction between layers. 4Hb-TaS₂, which is alternately stacked by superconductor 1H-TaS₂ and Mott insulator 1T-TaS₂, has attracted much attention because of its unique two-dimensional layered structure, excellent electronic properties and special interlayer charge transfer. At present, there is little research on how to regulate this special interlayer charge transfer, which makes the electrical properties of 4Hb-TaS₂ still have a large research space. In this paper, the surface potential difference of 4Hb-TaS₂ was studied by means of Kelvin probe force microscopy (KPFM), and the cleavage layer on its surface can be distinguished by combining the surface morphology information. T-H transformation was realized by high temperature annealing, and 4Hb-Ta_1-xTi_xS₂(x=0.005) was successfully prepared. On this basis, the influence of different element doping on the surface electrical properties of 4Hb-TaS₂ was explored. It is found that by doping different elements, the interlayer charge transfer ability of 4Hb-TaS₂ can be controlled and the surface potential difference can be affected. The surface potential difference of 4Hb-TaS₂ is obviously increased after Ti doping, but it is decreased after Se doping. In addition, it is found that 4Hb-TaS₂ is not only stacked alternately in T layer and H layer, but also has some stacking faults. The controllable regulation of interlayer charge transfer provides help for the in-depth study of interlayer charge transfer of this system material. At the same time, it also provides new inspiration for the study of interlayer charge transfer and surface electrical properties of other van der Waals materials.