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arXiv · 2505.22725

Kekul\'e order from diffuse nesting near higher-order Van Hove points

Jonas Beck·Jonathan Bodky·Matteo Dürrnagel·Ronny Thomale·Julian Ingham·Lennart Klebl·Hendrik Hohmann
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Abstract

Translation symmetry-breaking order is assumed to be suppressed by the lack of Fermi surface nesting near certain higher-order Van Hove singularities (HOVHS). We show the anisotropic band-flattening inherent to such HOVHS, combined with broadening of the Fermi surface due to elevated critical temperatures, results in the Fermi surface becoming approximately nested at a wavevector unrelated to the precise shape of the Fermi surface - leading to a $\sqrt{3}\times\sqrt{3}$ Kekul\'e density wave formation. The effect is demonstrated using unbiased renormalization group calculations for a model of the breathing kagome lattice. Our mechanism - termed diffuse nesting - represents an entirely new notion in the study of Fermi surface instabilities.

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Jonas Beck, Jonathan Bodky, Matteo Dürrnagel, Ronny Thomale, Julian Ingham, Lennart Klebl, Hendrik Hohmann. 2025-05-28. Kekul\'e order from diffuse nesting near higher-order Van Hove points. https://doi.org/10.1103/gwc6-1vv1

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