Superconducting VF with unusual delocalized electrons under high pressure

Area of Science:

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

Background:

• Superconductivity is prevalent in vanadium compounds (V-H, V-O, V-N) but not yet observed in vanadium fluorides.
• Vanadium-fluorine (V-F) systems are of significant interest for exploring new superconducting materials.

Purpose of the Study:

• To systematically investigate vanadium-fluorine compounds under high pressure.
• To identify novel stable stoichiometries and their superconducting properties.

Main Methods:

• Utilized first-principles swarm-intelligence structural search calculations.
• Analyzed high-pressure phases and predicted superconducting characteristics using Bardeen-Cooper-Schrieffer (BCS) theory.

Main Results:

• Identified two new stable high-pressure stoichiometries: VF and VF₂.
• Observed unique V-V interactions and delocalized electrons in VF, indicating conductivity.
• Predicted a superconducting transition temperature (T_c) of 0.85 K for C2/m VF, with low-frequency phonon modes being crucial.

Conclusions:

• The study reveals novel high-pressure phases of V-F compounds, including potential superconductors.
• Introduces VF and VF₂ as new stable stoichiometries under pressure with unique electronic properties.
• Provides a high-pressure phase diagram for V-F systems, aiding future research into their physical and chemical properties.