Emergent superconductivity in TaO₃ at high pressures

Area of Science:

• Condensed Matter Physics
• Materials Science
• Computational Chemistry

Background:

• Tantalum (Ta) and its chalcogenides display superconductivity.
• Ta-O compounds are typically semiconductors (e.g., Ta2O5).
• High-pressure phases of materials can exhibit novel electronic properties.

Purpose of the Study:

• To propose and investigate the existence of high-pressure metallic tantalum-oxygen (Ta-O) compounds.
• To explore the superconducting properties of these novel Ta-O phases.
• To elucidate the underlying mechanisms of superconductivity in these materials.

Main Methods:

• First-principles calculations were employed to predict stable high-pressure Ta-O compounds.
• Density Functional Theory (DFT) was used to analyze electronic band structures and phonon dispersions.
• Electron-phonon coupling calculations were performed to estimate superconducting transition temperatures (Tc).

Main Results:

• Five high-pressure metallic Ta-O compounds (TaO3, TaO2, TaO, Ta2O, Ta3O) were predicted.
• TaO3 exhibits superconductivity with an estimated Tc of 3.87 K at 200 GPa.
• Dynamically stable TaO3 at 50 GPa shows enhanced electron-phonon coupling and a higher Tc of up to 9.02 K.
• Superconductivity in TaO3 is linked to low-frequency phonons and Ta 5d/O 2p electron interactions.

Conclusions:

• High-pressure metallic Ta-O compounds, particularly TaO3, are predicted to be superconductors.
• The electronegativity and light atomic mass of oxygen significantly influence superconductivity in TaO3.
• These findings offer insights into high-pressure superconductivity mechanisms in transition metal oxides.