Electric Control of 2D Van Hove Singularity in Oxide Ultra-Thin Films

Divergent density of states (DOS) can induce extraordinary phenomena such as significant enhancement of superconductivity and unexpected phase transitions. Moreover, van Hove singularities (VHSs) lead to divergent DOS in 2D systems. Despite recent interest in VHSs, only a few controllable cases have been reported to date. In this work, by utilizing an atomically ultra-thin SrRuO3 film, the electronic structure of a 2D VHS is investigated with angle-resolved photoemission spectroscopy and transport properties are controlled. By applying electric fields with alkali metal deposition and ionic-liquid gating methods, the 2D VHS and the sign of the charge carrier are precisely controlled. Use of a tunable 2D VHS in an atomically flat oxide film could serve as a new strategy to realize infinite DOS near the Fermi level, thereby allowing efficient tuning of electric properties.

Automated summary

By utilizing an atomically ultra-thin SrRuO3 film, the electronic structure of a 2D van Hove singularity (VHS) is investigated and controlled using angle-resolved photoemission spectroscopy and transport properties. The 2D VHS and the sign of the charge carrier are precisely controlled by applying electric fields with alkali metal deposition and ionic-liquid gating methods. This tunable 2D VHS in an atomically flat oxide film could serve as a new strategy to achieve infinite density of states (DOS) near the Fermi level, enabling efficient tuning of electric properties.