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The recent discovery of the family of AV3Sb5 (A=K, Cs, Rb) metals has sparked great interest in the study of kagome lattice systems. These materials exhibit a plethora of intriguing low-temperature behaviour, as superconductivity, a charge density wave (CDW) and time-reversal symmetry breaking (TRSB) without magnetic ordering have all been found within these compounds. Although much effort has been devoted to understanding the physics of these materials in the last few years, there are still many unknowns. For instance, the nature of TRSB is still unclear, as is the mechanism that stabilizes the CDW found. In this work, we study a model of interacting electrons on the kagome lattice at a mean-field level. In particular, both a single-orbital model and a multi-orbital extension are considered. Our calculations reveal the presence of different interaction-driven CDW patterns, with the single-orbital model exhibiting a CDW phase compatible with the experimental findings. Furthermore, no traces were found of TRSB without magnetic ordering nor of ferromagnetism, in accordance with recent variational Monte Carlo calculations. Our results also suggest that the px and py orbitals of the in-plane Sb atoms might not be crucial for determining the physical properties of AV3Sb5 materials, while the van Hove singularities in the band structure could be playing a key role in this regard.

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Karim Chahine, SISSA
Seminar Room 0.01, ETP
Contact: Sebastian Diehl