Retainable Superconductivity and Structural Transition in 1T-TaSe₂ Under High Pressure

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid-State Chemistry

Background:

• Transition-metal dichalcogenides (TMDCs) are known for superconductivity (SC) and charge density wave (CDW) properties.
• The interplay between SC and CDW in TMDCs is a key area of research.

Purpose of the Study:

• To investigate the electronic properties and structural evolution of 1T-TaSe2 under pressure.
• To understand the relationship between structural phase transitions, CDW suppression, and superconductivity.

Main Methods:

• Systematic investigation of 1T-TaSe2 under varying pressures.
• Analysis of electronic properties and structural evolution.
• Observation of superconductivity and its transition temperature (Tc).

Main Results:

• Superconductivity was induced in 1T-TaSe2 at approximately 2.6 GPa.
• The transition temperature (Tc) increased with CDW suppression, reaching a maximum of ~5.1 K at 21.8 GPa.
• A structural transformation to a monoclinic C2/m phase occurred above 19 GPa, which retained superconductivity (~2.9 K) upon pressure release.

Conclusions:

• Superconductivity in 1T-TaSe2 is strongly influenced by both structural changes and the charge density wave state.
• The high-pressure monoclinic phase is responsible for the retained superconductivity in released samples.