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

Donghan Kim; Younsik Kim; Byungmin Sohn; Minsoo Kim; Bongju Kim; Tae Won Noh; Changyoung Kim

doi:10.1002/adma.202207188

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

Adv Mater. 2023 Apr;35(17):e2207188. doi: 10.1002/adma.202207188. Epub 2023 Mar 20.

Authors

Donghan Kim^{1

2}, Younsik Kim^{1

2}, Byungmin Sohn^{1

2}, Minsoo Kim^{1

2}, Bongju Kim^{1

2}, Tae Won Noh^{1

2}, Changyoung Kim^{1

2}

Affiliations

¹ Center for Correlated Electron Systems, Institute for Basic Science, Seoul, 08826, South Korea.
² Department of Physics and Astronomy, Seoul National University, Seoul, 08826, South Korea.

PMID: 36764325
DOI: 10.1002/adma.202207188

Abstract

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.

Keywords: Hall effect; angle-resolved photoemission spectroscopy; electronic structure; ionic liquid gating; oxide thin film; ruthenate; transport measurement; ultrathin film; van Hove singularity (VHS).

Abstract

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