Common Sublattice-Pure Van Hove Singularities in the Kagome Superconductors AV_{3}Sb_{5} (A=K, Rb, Cs)

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Kagome materials host correlated and topological quantum states.
• Van Hove singularities (VHSs) are key to electronic instabilities in these systems.
• The kagome superconductors AV3Sb5 exhibit unconventional charge density wave order, superconductivity, and electronic chirality, but the role of VHSs remains unclear.

Purpose of the Study:

• To investigate the nature of Van Hove singularities (VHSs) near the Fermi level in AV3Sb5.
• To understand the connection between VHSs and the emergent exotic orders in these materials.
• To clarify the electronic structure of AV3Sb5 and its deviations from theoretical predictions.

Main Methods:

• High-resolution polarization-dependent angle-resolved photoemission spectroscopy (ARPES).
• Comparison of experimental results with density-functional theory (DFT) predictions.

Main Results:

• A universal electronic structure was observed across AV3Sb5, differing from DFT predictions.
• Multiple common sublattice-pure VHSs were identified near the Fermi level.
• Strong V-d/Sb-p hybridization was found to drive VHS formation, promoting bond-order fluctuations and the charge density wave order.

Conclusions:

• Spectroscopic evidence confirms hybridization-driven VHS formation in kagome metals.
• The findings establish a unified framework for understanding intertwined electronic instabilities in AV3Sb5.
• This work sheds light on the fundamental mechanisms behind exotic phenomena in kagome superconductors.