Estudo teórico de bicamada de grafeno em superfície Cu (111)

• Ano de defesa: 2014
• Autor(a) principal: Souza, Everson dos Santos
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Espírito Santo; BR; Mestrado em Física; Centro de Ciências Exatas; UFES; Programa de Pós-Graduação em Física
• Palavras-chave em Português: Bilayer graphene; Cu (111) surface; Co, magnetic moment; DFT; Bicamada de grafeno; Superfície Cu(111); CO, momento magnético; Cobalto; Materiais nanoestruturados; Estrutura eletrônica; Carbono; Metais - Superfícies; Física; 53
• Link de acesso: http://repositorio.ufes.br/handle/10/7455

In this work, the energetic stability, electronic, and structural properties of graphenesheets adsorbed on Cu(111) surface have been examined through first principle calculationsbased on density functional theory (DFT). We have considered the adsorption on Cu(111)surface of (i) defect-free monolayer graphene (G) and defect-free bilayer graphene (BLG), (ii)bilayer graphene with substitutional defects of the Co atom. In (i) we have considered threedifferent possible configurations for formation of interfaces. We find that the formation ofG/Cu(111) and BLG/Cu(111) are exothermic processes, with adsorption energy of the 35.3meV/Å2and 39.2 meV/Å2on the most stable configurations, respectively. Moreover, we findto bilayer graphene an equilibrium distance between metal and interfacial graphene layer of2.89 Å, identical to the value for the monolayer. Thus, this results have been indicated thatthe adsorption of G and BLG on Cu(111) are guided by a weak physisorption. Additionally,the formation of G/Cu(111) and BLG/Cu(111) interfaces gives rise to the charge densityfluctuations and G and BLG on Cu(111) aren-type doped. As verified by Bader analysis,there exist a charge transfer from copper surface for G and BLG of the 0.0062 e 0.0058 e/Å2,respectively. In (ii) we studied substitutional defects of the Co atom in the topsheet ofBLG in two different atomic sites (BLG-Coaand BLG-Coßsystems), without the presenceof the metal substrate. In this case, our results have indicated that there is a non-zerototal magnetic moment in BLG-Coaand BLG-Coßsystems. Also, considering adsorption ofBLG-Coßon Cu(111) surface, we find that the formation of BLG-Coß/Cu(111) is an exothermicprocess, with adsorption energy of the 40.1 meV/Å2. Even though, we not find chemicalbond on graphene-metal interface or significant increase of adsorption energy, the totalmagnetic moment of BLG-Coßsystem is quenched when adsorbed on copper substrate, dueto predominant the charge transfer from Cu substrate for BLG-Coß.