Engineering higher order Van Hove singularities in two dimensions: the example of the surface layer of Sr₂RuO₄

The properties of correlated electron materials are often intricately linked to Van Hove singularities (VHs) in the vicinity of the Fermi energy. The class of these VHs is of great importance, with higher order ones -- with power-law divergence in the density of states -- leaving frequently distinct signatures in physical properties. We use a new theoretical method to detect and analyse higher order Van Hove singularities (HOVHs) in two-dimensional materials and apply it to the electronic structure of the surface layer of Sr₂RuO₄. We then constrain a low energy model of the VHs of the surface layer of Sr₂RuO₄ against angle-resolved photoemission spectroscopy and quasiparticle interference data to analyse the VHs near the Fermi level. We show how these VHs can be engineered into HOVHs.