On the engineering of higher-order Van Hove singularities in two dimensions

TL;DR

This paper introduces a new theoretical method to detect and analyze higher-order Van Hove singularities in two-dimensional materials, applying it to Sr₂RuO₄, and demonstrates how to engineer these singularities.

Contribution

A novel theoretical approach for identifying higher-order Van Hove singularities and applying it to real materials, enabling their engineering in two-dimensional systems.

Findings

Identified higher-order Van Hove singularities in Sr₂RuO₄ surface layer.

Constrained a low energy model using ARPES and quasiparticle interference data.

Showed how to engineer Van Hove singularities into higher-order types.

Abstract

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 VHS (HOVHS) in two-dimensional materials and apply it to the electronic structure of the surface layer of Sr$_2$RuO$_4$. We then constrain a low energy model of the VHS of the surface layer of Sr$_2$RuO$_4$ 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.