Coupling Between Electrons and Charge Density Wave Fluctuation and its Possible Role in Superconductivity

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Superconductivity often emerges in charge density wave (CDW) systems near a quantum critical point (QCP).
• The fundamental connection between CDW and superconductivity has remained elusive across various material classes.
• Understanding this interplay is crucial for designing novel superconducting materials.

Purpose of the Study:

• To investigate the coupling between electron and CDW fluctuations in 2H-Pd$_{x}$TaSe$_{2}$.
• To establish the essential link between CDW phenomena and the emergence of superconductivity.
• To explore the role of this coupling in mediating superconductivity.

Main Methods:

• Angle-resolved photoemission spectroscopy (ARPES) was used to probe electronic properties.
• Temperature and intercalation were varied to tune the CDW state.
• McMillan's equation was adapted to estimate superconducting critical temperatures.

Main Results:

• A temperature- and intercalation-dependent kink was observed in ARPES spectra, indicating electron-CDW coupling.
• This coupling occurs in both long- and short-range CDW phases.
• Coupling strength increases as long-range CDW order is suppressed, while energy scale decreases.
• Estimated superconducting critical temperatures align well with experimental values.

Conclusions:

• Evidence for a novel electron-CDW fluctuation coupling is presented.
• This coupling is a potential mediator for Cooper pairs, linking CDW and superconductivity.
• The findings offer new perspectives on competing orders in materials.