Enhanced nematicity emerging from higher-order Van Hove singularities

X Han, AP Schnyder, X Wu - Physical Review B, 2023 - APS
Physical Review B, 2023APS
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 two-dimensional 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 …
Motivated by the experimental identification of a higher-order Van Hove singularity (VHS) in kagome metals, we study electronic instabilities of two-dimensional 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, antiferromagnetism, superconductivity, and Pomeranchuk orders. Remarkably, there is a generic transition from superconductivity to a -wave Pomeranchuk order with increasing flavor number. Implications for the intriguing quantum states of kagome metals are also discussed.
American Physical Society