Charge density wave and superconductivity in 6R-TaS2

TL;DR

This study investigates the charge density wave and superconducting properties of the less-studied 6R-TaS2 polymorph, revealing multiple CDW transitions and superconductivity at low temperatures, expanding understanding of transition metal dichalcogenides.

Contribution

It provides detailed experimental evidence of CDW and superconductivity in 6R-TaS2, a polymorph less explored compared to other TaS2 forms.

Findings

Multiple charge density wave transitions observed between room temperature and 650K.

Superconductivity detected around 3.5 K with type-II characteristics.

Charge density wave transition occurs near 305 K.

Abstract

The layered transition metal dichalcogenide compounds 1T-TaS2 and 4H-TaS2 are well known for their exotic properties, which include charge density wave, superconductivity, Mott transition, etc., and lately quantum spin liquid. Here, we report the magnetic, transport and transmission electron microscopy study of the charge density wave and superconductivity in 6R-TaS2 which is a relatively less studied polymorph of this dichalcogenide TaS2. Our high temperature electron microscopy reveals multiple charge density wave transitions between room temperature and 650K. Magnetization, and the electrical resistivity measurements in the temperature range of 2-400 K reveal that 6R-TaS2 undergoes a charge density wave transition around 305 K and is followed by a transition to a superconducting state around 3.5 K. The low temperature specific heat measurement exhibits anomaly associated with the superconducting transition around 2.4 K. The estimated Ginzburg Landau parameter suggests that this compound lies at the extreme limit of type-II superconductivity.