title: The effect of doping on the energetics and quantum conductance in graphene nanoribbons with a metallocene adsorbate.
abstract: Based on a PBE-D2 calculation that empirically includes van der Waals interactions to the standard GGA approximation of Perdew, Berke, and Ernzerhof, we have investigated the adsorption of ferrocene or ruthenocene on pristine and X-doped graphene (GrS) or graphene nanoribbons (GNRs), where X (=B or N) is a p-type or n-type heteroatom. First, we find that van der Waals interactions play a dominant role in the adsorption. Second, we find that metallocene adsorption on doped GNRs introduces different effects in the low-bias conductance, not far from the linear response regime, of GNRs depending upon the doping type. Adsorption on undoped or p-type GNRs brings about a slight reduction in conductance due to an introduction of quasi-bound states just below the Fermi level. No appreciable reduction is expected in n-type GNRs because those states are introduced far below the Fermi level.
authors.affiliation: Department of Nano and Advanced Materials, College of Engineering, Jeonju University, Hyoja-dong, Wansan-ku, Chonju, Chonbuk 560-759, South Korea. hsk@jj.ac.kr
authors.forename: Hong Seok
authors.initials: HS
authors.lastname: Kang
authors.forename: Anup
authors.initials: A
authors.lastname: Pramanik