Abstract Body

NbS₂, a type of layered transition metal dichalcogenide, has polytypes. The 2H polytype shows a superconducting transition at about 6 K. The interlayers of 2H-NbS₂ are stacked by van der Waals forces, allowing the intercalation of ions [1, 2]. The superconducting transition temperature (T_c) of alkali metal-intercalated NbS₂ increases as the ionic radius of the alkali metal rises [2]. Depending on the increase in the ionic radius, the two-dimensionality of the NbS₂ layer is enhanced, suggesting it affects the superconducting properties. However, the detailed relationship between the ionic radius and superconducting properties has not been revealed.

In this study, single crystals of Cs- or K-intercalated NbS₂ were synthesized by using the flux method with CsCl and/or KCl. We found that these single crystals were grown by changing the combination of the flux. The composition analysis by Energy Dispersive X-ray Spectroscopy shows that the intercalation ratio of Cs or K ion is about 10 % in the prepared samples. These samples exhibit T_c at about 3 K in the electrical resistivity measurements. This resistivity result indicates that the T_c did not depend on the ionic radius, which is contrary to the previous result. In this talk, we will discuss the detailed method of synthesis of ion-intercalated single crystals using the flux method and the effect of ion intercalation of Cs and K ions on the superconducting properties.

References

[1] A. Lerf, et al., Mater. Res. Bull. 14, 797-805 (1979).
[2] M. Nagao, et al Z. Naturforsch. 76, 0123 (2021).

Keywords: flux, single crystal, intercalate, layered materials