Charge-density-wave-induced bands renormalization and energy gaps in a kagome superconductor RbV3Sb5

TL;DR

This study visualizes how charge density waves in RbV3Sb5 cause bands renormalization and energy gaps, highlighting the importance of van Hove singularities in the material's electronic ordering and superconductivity.

Contribution

It provides direct ARPES evidence of CDW-induced band shifts and energy gaps in RbV3Sb5, emphasizing the role of van Hove singularities in phase mechanisms.

Findings

Bands shift to high-binding energy near CDW transition

Partial gapping of Fermi surfaces observed

Residual states may contribute to superconductivity

Abstract

Recently discovered Z2 topological kagome metals AV3Sb5 (A = K, Rb, and Cs) exhibit charge density wave (CDW) phases and novel superconducting paring states, providing a versatile platform for studying the interplay between electron correlation and quantum orders. Here we directly visualize CDW-induced bands renormalization and energy gaps in RbV3Sb5 using angle-resolved photoemission spectroscopy, pointing to the key role of tuning van Hove singularities to the Fermi energy in mechanisms of ordering phases. Near the CDW transition temperature, the bands around the Brillouin zone (BZ) boundary are shifted to high-binding energy, forming an "M"-shape band with singularities near the Fermi energy. The Fermi surfaces are partially gapped and the electronic states on the residual ones should be possibly dedicated to the superconductivity. Our findings are significant in understanding CDW formation and its associated superconductivity.