title: One-atom-thick 2D copper oxide clusters on graphene.
abstract: The successful isolation and remarkable properties of graphene have recently triggered investigation of two-dimensional (2D) materials from layered compounds; however, one-atom-thick 2D materials without bulk layered counterparts are scarcely reported. Here we report the structure and properties of novel 2D copper oxide studied by experimental and theoretical methods. Electron microscopy observations reveal that copper oxide can form monoatomic layers with an unusual square lattice on graphene. Density functional theory calculations suggest that oxygen atoms at the centre of the square lattice stabilizes the 2D Cu structure, and that the 2D copper oxide sheets have unusual electronic and magnetic properties different from 3D bulk copper oxide.
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan. e.kano0727@gmail.com and National Institute for Materials Science, Tsukuba, 305-0047, Japan.
authors.forename: Emi
authors.identifier: http://orcid.org/0000-0001-6134-4980
authors.initials: E
authors.lastname: Kano
authors.affiliation: National University of Science and Technology MISIS, Moscow, 119049, Russia. pbsorokin@misis.ru and Emanuel Institute of Biochemical Physics RAS, Moscow, 119334, Russia.
authors.forename: Dmitry G
authors.identifier: http://orcid.org/0000-0003-3320-6657
authors.initials: DG
authors.lastname: Kvashnin
authors.affiliation: National Institute for Materials Science, Tsukuba, 305-0047, Japan and National Institutes for Quantum and Radiological Science and Technology, Tokai, 310-1106, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Sakai
authors.affiliation: Emanuel Institute of Biochemical Physics RAS, Moscow, 119334, Russia.
authors.forename: Leonid A
authors.initials: LA
authors.lastname: Chernozatonskii
authors.affiliation: National University of Science and Technology MISIS, Moscow, 119049, Russia. pbsorokin@misis.ru and Emanuel Institute of Biochemical Physics RAS, Moscow, 119334, Russia and Technological Institute of Superhard and Novel Carbon Materials, Moscow, 142190, Russia.
authors.forename: Pavel B
authors.initials: PB
authors.lastname: Sorokin
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan. e.kano0727@gmail.com and National Institute for Materials Science, Tsukuba, 305-0047, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Hashimoto
authors.affiliation: Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba, 305-8573, Japan. e.kano0727@gmail.com and National Institute for Materials Science, Tsukuba, 305-0047, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Takeguchi