Growth and Electronic Structure of Copper Oxide Monolayer Epitaxial Films.

Kim, Youngdo; Gil, Byeongjun; Kim, Jinkwon; Lee, Yeonjae; Kim, Donghan; Hahn, Sungsoo; Noh, Tae Won; Kim, Miyoung et al. · Nano Lett · 2023

basic_science · Level V

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Abstract

Copper-based high-temperature superconductors share a common feature in their crystal structure, which is the presence of a CuO<sub>2</sub> plane, where superconductivity takes place. Therefore, important questions arise as to whether superconductivity can exist in a single layer of the CuO<sub>2</sub> plane and, if so, how such superconductivity in a single CuO<sub>2</sub> plane differs from that in a bulk cuprate system. To answer these questions, studies of the superconductivity in cuprate monolayers are necessary. In this study, we constructed a heterostructure system with a La<sub>2-<i>x</i></sub>Sr<sub><i>x</i></sub>CuO<sub>4</sub> (LSCO) monolayer containing a single CuO<sub>2</sub> plane and measured the resulting electronic structures. Monolayer LSCO has metallic and bulk-like electronic structures. The hole doping ratio of the monolayer LSCO is found to depend on the underlying buffer layer due to the interface effect. Our work will provide a platform for research into ideal two-dimensional cuprate systems.