Superconductivity in Metal-Rich Chalcogenide Ta₂Se

Area of Science:

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

Background:

• Metal-rich chalcogenides feature diverse structures and properties due to metal-metal bonding.
• Tantalum selenide (Ta₂Se) exhibits a layered tetragonal structure (P4/nmm).

Purpose of the Study:

• To investigate the physical properties of Ta₂Se, focusing on superconductivity.
• To elucidate the electronic structure and its relation to superconductivity in Ta₂Se.

Main Methods:

• Synthesis of Ta₂Se via arc-melting and solid-state pellet methods.
• Experimental measurements including magnetic susceptibility, resistivity, and heat capacity.
• First-principles calculations to analyze electronic band structure and density of states.

Main Results:

• Ta₂Se exhibits bulk superconductivity with a critical temperature (Tc) of 3.8(1) K.
• First-principles calculations show Ta 5d orbitals dominate the Fermi level.
• Van Hove singularities near the Fermi level, enhanced by spin-orbit coupling, are identified.

Conclusions:

• Ta₂Se is a novel superconductor with properties distinct from other tantalum alloys or TaSe₂.
• The electronic structure, particularly flat bands and van Hove singularities, is crucial for superconductivity in Ta₂Se.