title: Self-assembly of metal atoms (Na, K, Ca) on graphene.
abstract: A thorough search of the distribution pattern of Na, K, and Ca atoms on graphene surface, carried out using a synergistic combination of density functional theory and particle swarm optimization algorithm, yielded some unusual results. The equilibrium distribution is concentration and metal dependent; the metal atoms distribute uniformly when their coverage ratio M : C (M = Na, K, Ca) is 1 : 6, but Na and Ca atoms self-assemble to form parallel quasi-one-dimensional chains when their coverage is reduced to 1 : 8. At the higher concentration (M : C = 1 : 6), electron-phonon coupling calculations further show that the NaC6 is a superconductor with critical temperature of 5.8 K, which is the highest value among all the stable alkali or alkaline-earth metal decorated monolayer graphene systems studied to-date. At the lower concentration (M : C = 1 : 8) and depending on metal species, well-aligned atomic metal chains interact with graphene with varying intensity, making it possible to achieve either rigid or non-rigid band doping in graphene.
authors.affiliation: Department of Physics, Virginia Commonwealth University, Richmond, VA 23284, USA. pjena@vcu.edu.
authors.forename: Jian
authors.initials: J
authors.lastname: Zhou
authors.forename: Shunhong
authors.initials: S
authors.lastname: Zhang
authors.forename: Qian
authors.initials: Q
authors.lastname: Wang
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Kawazoe
authors.forename: Puru
authors.initials: P
authors.lastname: Jena