Synthesis and structure of a non-van-der-Waals two-dimensional coordination polymer with superconductivity

Area of Science:

• Materials Science
• Solid-State Physics
• Chemistry

Background:

• Two-dimensional conjugated coordination polymers show excellent charge transport.
• Copper-based benzenehexathiol (Cu-BHT) is a rare superconductor, but its atomic structure is unknown.
• Understanding the atomic structure is key to understanding Cu-BHT superconductivity.

Purpose of the Study:

• To synthesize high-quality single crystals of Cu-BHT.
• To resolve the atomic structure of Cu-BHT.
• To investigate the relationship between the atomic structure and electrical properties, including superconductivity.

Main Methods:

• Single crystal synthesis of Cu-BHT.
• Crystallographic analysis to determine atomic structure.
• Electrical conductivity measurements at various temperatures.

Main Results:

• High-crystallinity single crystals of Cu3BHT were synthesized.
• A quasi-two-dimensional kagome structure with non-van der Waals interlayer Cu-S covalent bonds was revealed.
• Intrinsic metallic behavior was observed, with conductivity up to 10^3 S/cm at 300 K and 10^4 S/cm at 2 K.
• Superconductivity was detected at 0.25 K, linked to enhanced electron-electron interactions and electron-phonon coupling.

Conclusions:

• The atomic structure of Cu-BHT was resolved, revealing a unique kagome lattice with covalent interlayer bonds.
• A direct correlation between crystal structure and electrical properties, including superconductivity, was established.
• This work provides a foundation for developing advanced superconductor coordination polymers for quantum devices.