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arXiv · 2511.14614

Non-Fermi-liquid behaviour and Fermi-surface expansion induced by van Hove-driven ferromagnetic fluctuations: the D-TRILEX analysis

Ilia S. Dedov·Andrey A. Katanin·Evgeny A. Stepanov
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Abstract

We consider the electronic and magnetic properties of the Hubbard model on a square lattice with the Fermi level near van Hove singularity and the ratio of the next-nearest-neighbor and nearest-neighbor hoppings $t'/t=-0.45$, which favours the ferromagnetic instability. We find, that a self-consistent consideration of the ferromagnetic fluctuations within the D-TRILEX approach results in the splitting of the electronic spectral function at low temperatures. This splitting exhibits only a weak momentum dependence, and only one of the split bands crosses the Fermi level. As a result, the Fermi surface itself remains unsplit, but its area increases, reflecting the presence of non-Fermi-liquid electronic excitations. We show that both the self-consistent account of the non-local contributions to the electronic self-energy and the proper treatment of electron interaction vertices in D-TRILEX are important to obtain this behaviour.

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Ilia S. Dedov, Andrey A. Katanin, Evgeny A. Stepanov. 2025-11-18. Non-Fermi-liquid behaviour and Fermi-surface expansion induced by van Hove-driven ferromagnetic fluctuations: the D-TRILEX analysis. https://doi.org/10.1103/46h3-sprg

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