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arXiv · 2302.02906

Enhanced nematicity emerging from higher-order van Hove singularities

Xinloong Han·Andreas P. Schnyder·Xianxin Wu
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Abstract

Motivated by the experimental identification of a higher-order van Hove singularity (VHS) in AV$_3$Sb$_5$ kagome metals, we study electronic instabilities of 2D lattice models with higher-order VHS and flavor degeneracy. In contrast to conventional VHSs, the larger power-law density of states and the weaker nesting propensity of higher-order VHSs conspire together to generate distinct competing instabilities. After discussing the occurrence of higher-order VHSs on square and kagome lattice models, we perform unbiased renormalization group calculations to study competing instabilities and find a rich phase diagram containing ferromagnetism, anti-ferromagnetism, superconductivity and Pomeranchuk orders. Remarkably, there is a generic transition from superconductivity to a $d$-wave Pomeranchuk order with increasing flavor number. Implications for the intriguing quantum states of AV$_3$Sb$_5$ kagome metals are also discussed.

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Xinloong Han, Andreas P. Schnyder, Xianxin Wu. 2023-02-06. Enhanced nematicity emerging from higher-order van Hove singularities. https://doi.org/10.1103/physrevb.107.184504

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