A single-component molecular superconductor.

Area of Science:

• Materials Science
• Condensed Matter Physics
• Solid State Chemistry

Background:

• Single-component molecular conductors are promising for electronic applications.
• The compound [Ni(hfdt)2] exhibits semiconducting properties at ambient pressure.
• Understanding pressure effects is crucial for tuning material properties.

Purpose of the Study:

• To investigate the pressure dependence of resistivity in [Ni(hfdt)2].
• To determine the pressure-induced superconducting transition.
• To elucidate the relationship between crystal structure, electronic band structure, and superconductivity.

Main Methods:

• Four-probe resistivity measurements up to ~10 GPa using a diamond anvil cell.
• First-principle calculations of crystal and electronic band structures at high pressures (6-11 GPa).

Main Results:

• The low-temperature insulating phase is suppressed above 7.5 GPa.
• Superconducting transition observed around 7.5-8.7 GPa with a maximum Tc of 5.5 K.
• Calculations show semiconducting band structure up to 6 GPa, with electron and hole Fermi surfaces appearing at 8 GPa.

Conclusions:

• High pressure induces a superconducting phase in [Ni(hfdt)2].
• The emergence of superconductivity correlates with the suppression of the insulating phase and the appearance of Fermi surfaces.
• First-principle calculations support the experimental observations of pressure-induced electronic structure changes.