Enhanced anisotropic superconductivity in the topological nodal-line semimetal InxTaS2

TL;DR

This paper reports the synthesis of InxTaS2, a topological nodal-line semimetal exhibiting coexisting charge density wave and superconductivity, with enhanced anisotropic critical fields linked to its topological band structure.

Contribution

It introduces a new layered topological material InxTaS2 with coexisting CDW and superconductivity, and explains the anisotropic critical field enhancement through topological band effects.

Findings

Superconductivity appears below 0.69 K in InxTaS2.

A 2x2 commensurate charge density wave is observed at low temperature.

Enhanced anisotropy ratio of upper critical field is linked to topological band structure.

Abstract

Coexistence of topological bands and charge density wave (CDW) in topological materials has attracted immense attentions because of their fantastic properties, such as axionic-CDW, three-dimensional quantum Hall effect, etc. In this work, a nodal-line semimetal InxTaS2 characterized by CDW and superconductivity is successfully synthesized, whose structure and topological bands (two separated Wely rings) are similar to In0.58TaSe2. A 2 x 2 commensurate CDW is observed at low temperature in InxTaS2, identified by transport properties and STM measurements. Moreover, superconductivity emerges below 0.69 K, and the anisotropy ratio of upper critical field [Gamma = H||ab c2(0)=H||c c2(0)] is significantly enhanced compared to 2H-TaS2, which shares the same essential layer unit. According to the Lawrence-Doniach model, the enhanced Gamma may be explained by the reduced effective mass in kx-ky plane, where Weyl rings locate. Therefore, this type of layered topological systems may offer a platform to investigate highly anisotropic superconductivity and to understand the extremely large upper critical field in the bulk or in the two-dimensional limit.