Superconductivity in compressed quasi-one-dimensional face-sharing hexagonal perovskite chalcogenides.

Area of Science:

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

Background:

• Traditional oxide perovskite superconductors feature 3D or 2D layered structures with corner-sharing octahedra.
• Emerging materials with novel connectivity offer new avenues for exploring superconductivity mechanisms.

Purpose of the Study:

• To investigate superconductivity in hexagonal perovskite chalcogenides with face-sharing connectivity.
• To characterize the superconducting properties of barium titanium trisulfide (BaTiS3) under pressure.

Main Methods:

• Electrical resistance and magnetic susceptibility measurements.
• Synchrotron X-ray diffraction for structural analysis.
• Density functional theory (DFT) calculations.

Main Results:

• Anisotropic superconductivity observed in compressed BaTiS3, with a critical temperature (Tc) up to ~9.3 K at a carrier concentration of 1.6 × 10^21 cm^-3.
• The superconducting phase maintains a hexagonal perovskite structure with quasi-1D infinite titanium hexasulfide chains.
• Substituting sulfur with selenium in BaTiX3 (X=S, Se) decreased the maximum Tc, indicating the importance of electron-phonon interactions.

Conclusions:

• Discovery of quasi-1D superconductivity in a novel hexagonal perovskite chalcogenide system.
• Electron-phonon interactions are identified as a key mechanism for superconductivity in BaTiX3.
• This quasi-1D material provides a new platform for understanding emerging electronic states in perovskites.