Pressure-Induced Dimensional Crossover in a Kagome Superconductor.

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Kagome superconductors (AV3Sb5) show complex high-pressure phase diagrams.
• A novel superconducting phase emerges under pressure, but its origin is unclear.

Purpose of the Study:

• Investigate the origin of the high-pressure superconducting phase in CsV3Sb5.
• Understand the relationship between pressure-induced structural changes and superconductivity.

Main Methods:

• High-pressure electrical resistance measurements up to 150 GPa.
• High-pressure X-ray diffraction (XRD) studies.
• First-principles electronic structure calculations.

Main Results:

• The new superconducting phase is robust and directly correlated with interlayer Sb2-Sb2 bond formation.
• High pressure induces a 2D to 3D dimensional crossover.
• Sb2-Sb2 bonding elevates the Sb2 pz orbital across the Fermi level, increasing density of states and Tc.
• A topological phase transition is induced by the dimensional crossover.

Conclusions:

• Interlayer Sb2-Sb2 interactions are key to the high-pressure superconducting phase in AV3Sb5.
• Dimensional crossover under pressure drives topological transitions and influences Tc.
• Findings are relevant for understanding superconductivity in other layered materials.