Effects of Selenium doping on the charge density wave and superconductivity of 4H_b-TaS₂

The MX₂ family is well known for their remarkable tunability as well as their rich physics, especially when two or more different compounds are stacked in the form of heterostructures. 4H_b-TaS₂, which was first synthesized in 1972 as a naturally occurring heterostructure of alternating 1H and 1T layers[1], has recently been revisited as a promising platform for topological superconductivity [2,3]. These studies have used 1% Se doping to stabilize superconductivity in this material, but it comes at the cost of suppressing the charge density wave (CDW) order in the 1H layers [4]. In this work, we investigate the role of Se substitution in stabilizing the superconducting phase of 4H_b-TaS₂ and its connection to CDW. We compare transport measurements of pure and lightly doped (1% Se) 4H_b-TaS₂ single crystals. While the pristine sample exhibits a broader superconducting transition, which completes at a much lower temperature, it remains a valuable reference for understanding the intrinsic interplay between CDW order and superconductivity in this naturally-heterostructured system.

References:

1. Di Salvo, F. J., et al. "Preparation and properties of a new polytype of tantalum disulfide (4Hb-TaS2)." Journal of Physics and Chemistry of Solids 34.8 (1973): 1357-1362.

2. Ribak, A., et al. "Chiral superconductivity in the alternate stacking compound 4Hb-TaS2." Science advances 6.13 (2020): eaax9480.

3. Silber, I., et al. "Two-component nematic superconductivity in 4Hb-TaS2." Nature Communications 15.1 (2024): 824.

4. Yang, F. Z., et al. "Charge density waves in the 2.5-dimensional quantum heterostructure." Physical Review B 111.4 (2025): L041101.