Strong enhancement of superconductivity at high pressures within the charge-density-wave states of 2H-TaS 2 and 2H-TaSe 2

TL;DR

This study demonstrates significant enhancement of superconductivity in 2H-TaS2 and 2H-TaSe2 under high pressure, revealing the interplay between charge density waves and superconductivity.

Contribution

It provides detailed measurements of how superconducting and charge density wave critical temperatures evolve with pressure in these materials, highlighting the pressure-induced enhancement of superconductivity.

Findings

Superconducting transition temperature (Tc) increases up to 8.5 K in 2H-TaS2 at 9.5 GPa.

Superconducting transition temperature (Tc) reaches 8.2 K in 2H-TaSe2 at 23 GPa.

A kink in TCDW at about 4 GPa indicates a lock-in transition from incommensurate to commensurate CDW.

Abstract

We present measurements of the superconducting and charge density wave critical temperatures (Tc and TCDW) as a function of pressure in the transition metal dichalchogenides 2H-TaSe2 and 2H-TaS2. Resistance and susceptibility measurements show that Tc increases from temperatures below 1 K up to 8.5 K at 9.5 GPa in 2H-TaS2 and 8.2 K at 23 GPa in 2H-TaSe2. We observe a kink in the pressure dependence of TCDW at about 4 GPa that we attribute to the lock-in transition from incommensurate CDW to commensurate CDW. Above this pressure, the commensurate TCDW slowly decreases coexisting with superconductivity within our full pressure range.