Superconductivity and charge density wave formation in lithium-intercalated 2H-Ta S2

Abstract

We systematically investigated the superconducting properties and the interplay between charge density waves (CDWs) and superconductivity (SC) in lithium-intercalated 2H-TaS2. By gradually increasing the lithium content x, the CDW formation temperature is continuously suppressed, and the onset temperature of SC is increased with a maximum transition temperature Tc=3.5K for x=0.096. The bulk nature of SC is confirmed by a superconducting shielding fraction of the order of unity for this composition. The electronic contribution to the specific heat and Hall resistivity data demonstrates that the CDW weakens with lithium intercalation, thereby indirectly increasing the carrier density and boosting SC. While the sign of the charge carriers in undoped 2H-TaS2 changes from electronlike to hole type near the CDW formation temperature ∼75K, the lithium-intercalated LixTaS2 shows predominantly hole-type carriers in the CDW phase even for very low lithium content.