Multiband Superconductivity with Sign-Preserving Order Parameter in Kagome Superconductor CsV_{3}Sb_{5}

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Kagome superconductors, such as CsV_{3}Sb_{5}, exhibit complex electronic properties.
• Understanding the interplay between superconductivity and charge density waves (CDW) is crucial for novel quantum materials.

Purpose of the Study:

• To investigate the nature of superconductivity in CsV_{3}Sb_{5} at an atomic level.
• To elucidate the relationship between charge density waves and superconducting gaps.

Main Methods:

• High-resolution scanning tunneling microscopy and spectroscopy (STM/STS).
• Measurements performed at ultralow temperatures on CsV_{3}Sb_{5} surfaces.

Main Results:

• Observation of two distinct superconducting gaps, indicating multiband superconductivity.
• In-gap states induced by magnetic impurities suggest a sign-preserving (s-wave) superconducting order parameter.
• Differential density of states (DOS) reveals varying interplay between CDW and superconductivity across different electronic bands.

Conclusions:

• Superconducting gaps are likely isotropic on Fermi surface sections less involved in CDW.
• Anisotropic CDW gaps correlate with anisotropic superconducting gaps.
• Residual zero-energy states are attributed to small superconducting gaps on specific Fermi pockets, offering insights into CsV_{3}Sb_{5} superconductivity.