Using controlled disorder to probe the interplay between charge order and superconductivity in NbSe₂

Area of Science:

• Condensed Matter Physics
• Materials Science

Background:

• The relationship between superconductivity and charge-density wave (CDW) order in 2H-NbSe2 is complex and not fully understood.
• Disrupting these competing orders can illuminate their underlying interactions.

Purpose of the Study:

• To investigate the impact of artificially introduced disorder on the interplay between superconductivity and CDW in 2H-NbSe2.
• To understand how disorder affects the transition temperatures and the nature of these orders.

Main Methods:

• Electron irradiation was used to introduce disorder into 2H-NbSe2 crystals.
• Measurements included in-plane resistivity, Hall resistivity, X-ray scattering, and London penetration depth.

Main Results:

• Superconducting transition temperature (Tc) showed non-monotonic behavior with increasing disorder.
• Charge-density wave transition temperature (TCDW) monotonically decreased and vanished at a critical dose.
• Short-range CDW order was observed to survive above the critical dose where long-range order disappeared.
• Superconductivity persisted to higher disorder levels, suggesting a fully gapped state.

Conclusions:

• CDW order initially competes with superconductivity but later assists it.
• The disappearance of long-range CDW order significantly suppresses superconductivity.
• Short-range CDW correlations play a role in the observed superconducting properties.