Atomistic origin of an ordered superstructure induced superconductivity in layered chalcogenides

Area of Science:

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

Background:

• Collective electronic states, such as charge density waves (CDW) and superconductivity, are crucial in low-dimensional electron systems.
• Understanding the atomistic and physical nature of electronic structures is key to elucidating their interplay and impact on material properties.
• The superconducting mechanism in systems exhibiting exotic electronic states remains incompletely understood.

Purpose of the Study:

• To investigate the role of atomic ordering in star-of-David clusters on superconductivity within the layered chalcogenide 1T-TaS2-xSex.
• To clarify the relationship between lattice degrees of freedom and electronic properties in the context of superconductivity and charge density waves.
• To explore the impact of specific atomic arrangements on the manifestation and suppression of superconductivity.

Main Methods:

• Advanced electron microscopy was employed to reveal the atomic structure of 1T-TaS2-xSex.
• Chemical substitution (selenium for sulfur) was used to tune the electronic properties and induce superconductivity.
• Correlation of structural observations with the presence and absence of superconductivity and Mott metal-insulator transitions.

Main Results:

• Evidence of an ordered superstructure within star-of-David clusters, specifically involving selenium and sulfur atoms surrounding tantalum.
• This ordered superstructure was found to be present exclusively in regions where superconductivity manifests in 1T-TaS2-xSex.
• The ordered superstructure was observed to be destructible, coinciding with the occurrence of the Mott metal-insulator transition.

Conclusions:

• Ordering of selenium and sulfur atoms within star-of-David clusters can significantly boost superconductivity in 1T-TaS2-xSex.
• The findings highlight a novel connection between lattice structure, specifically atomic ordering, and superconductivity in layered chalcogenides.
• This research provides a new perspective on the interplay between lattice and electronic degrees of freedom, crucial for understanding superconducting mechanisms.