title: RKKY interaction in heavily vacant graphene.
abstract: Dirac electrons in clean graphene can mediate the interactions between two localized magnetic moments. The functional form of the RKKY interaction in pristine graphene is specified by two main features: (i) an atomic-scale oscillatory part determined by a wavevector Q connecting the two valleys; with doping another longer range oscillation appears which arises from the existence of an extended Fermi surface characterized by a momentum scale kF; (ii) an algebraic R(α) decay in large distances where the exponent α =- 3 is a distinct feature of undoped Dirac sea in two dimensions. In this work, we investigate the effect of a few per cent vacancies on the above properties. Depending on the doping level, if the chemical potential lies on the linear part of the density of states, the exponent α remains at -3 even in vacant graphene. Otherwise α reduces towards more negative values. Presence of vacancies washes out both atomic-scale and Friedel oscillations of the RKKY interaction. The absence of atomic-scale oscillations indicates the destruction of two-valley structure of the parent graphene material. However, the absence of Friedel oscillations upon 'alloying' with vacancies indicates that a quantum ground state of heavily vacant doped graphene is not given by a unique kF momentum scale.
authors: Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran.
authors: Alireza
authors: A
authors: Habibi
authors: S A
authors: SA
authors: Jafari
mesh_terms: D003198:Computer Simulation; D004583:Electrons; D006108:Graphite / Q000737:chemistry*; D060526:Magnetic Fields; D008956:Models, Chemical; D013499:Surface Properties
chemical_list: D006108:Graphite