Correlated electrons in transition metal oxides (TMOs) exhibit a variety of emergent phases. When TMOs are confined to a single-atomic-layer thickness, experiments so far have shown that they usually lose diverse properties and become insulators. In an attempt to extend the range of electronic phases of the single-atomic-layer oxide, we search for a metallic phase in a monolayer-thick epitaxial SrRuO3 film. Combining atomic-scale epitaxy and angle-resolved photoemission measurements, we show that the monolayer SrRuO3 is a strongly correlated metal. Systematic investigation reveals that the interplay between dimensionality and electronic correlation makes the monolayer SrRuO3 an incoherent metal with orbital-selective correlation. Furthermore, the unique electronic phase of the monolayer SrRuO3 is found to be highly tunable, as charge modulation demonstrates an incoherent-to-coherent crossover of the two-dimensional metal. Our work emphasizes the potentially rich phases of single-atomic-layer oxides and provides a guide to the manipulation of their two-dimensional correlated electron systems.
@article{arxiv.2109.11090,
title = {Observation of metallic electronic structure in a single-atomic-layer oxide},
author = {Byungmin Sohn and Jeong Rae Kim and Choong H. Kim and Sangmin Lee and Sungsoo Hahn and Younsik Kim and Soonsang Huh and Donghan Kim and Youngdo Kim and Wonshik Kyung and Minsoo Kim and Miyoung Kim and Tae Won Noh and Changyoung Kim},
journal= {arXiv preprint arXiv:2109.11090},
year = {2021}
}