Atomic and electronic structure of simple metal/graphene and complex metal/graphene/metal interfaces

Abstract

Atomic and electronic structure of simple metal/graphene and complex metal/graphene/metal interfaces Structural, electronic, and magnetic properties of simple interfaces (graphene on top of metallic substrate) and complex interfaces (a single metallic adlayer on a simple graphene/metal system, either on top or between the graphene and metallic substrate) have been studied using density functional theory. Two types of simple interfaces with strong (Ni/graphene) and weak (Cu/graphene) bonding were considered. In addition to binding energies and interface distances, which are used to quantify the strength of graphene-substrate interactions, the bonding in simple and complex interfaces was analyzed using charge density distributions and bond orders. Substantial enhancement of metallic substrate/graphene binding was observed in complex interfaces, consisting of Ni monolayer on top of simple {Ni or Cu}/graphene interface. The increase of substate-graphene bonding in such complex interfaces is accompanied by weakening in-plane C-C bonds in graphene, as quantified by the bond orders. A weak ferrimagnetism in graphene, i.e. unequal magnetic moments -0.04 µ B and +0.06 µ B on C atoms, is induced by a ferromagnetic Ni substrate. The strength of graphene-substrate interactions is also reflected in simulated STM images.

Prospects of Spin Catalysis on Spin-Polarized Graphene Heterostructures

“…Among several possible graphene/Ni(111) interfaces, the top:fcc (carbon atoms are placed atop of top and fcc positions of nickel lattice) and hcp:fcc (carbon atoms are placed atop of hcp and fcc positions) configurations have been reported experimentally [31,32] to result in the lowest and highest energy chemi-and physisorbed graphene/Ni(111) heterostructures, respectively. The electronic structure calculations [33][34][35][36][37] confirmed the experimental findings. The deposition of graphene on ferromagnetic supports (in particular on Ni(111) surface) leads to C 2p z -states spin polarization (see, for example, [28,38] ) and some hybridization between graphene p-and Ni 3d valence bands.…”

“…[28] The graphene-Ni(111) distances for the top:fcc and hcp:fcc configurations are 2.08 and 3.21 Å , respectively, in comparison with the experimental [64,65] (2.14 and 2.80 Å , respectively), Perdew Burke Ernzerhof DFT (PBE) [65,66] (2.13 and 3.05 Å , respectively), and PBE taking into account van der Waals terms (vdW) [67] (2.12 and 3.76 Å , respectively) data. Previous LDA calculations [28,68] of both configurations give very similar graphene-Ni(111) distances (2.06, 3.62 and 2.04, 3.24 Å , respectively). Our calculation model qualitatively reproduces the experimental atomic structure and agrees with previous electronic structure calculations.…”

Hole doping, hybridization gaps, and electronic correlation in graphene on a platinum substrate

“…Alternatively, graphene itself can play an important role in enhancing functionality of other materials or devices such as the electrocatalytic effect of Pt 5,6 or solar cells as a counter electrode 7 . The key factor determining the nature of such cooperation is elec-tronic interactions between graphene and the transition-metals 8 .…”

Artificially lattice-mismatched graphene/metal interface: Graphene/Ni/Ir(111)

“…On the other hand, the term strong appears inappropriate if intended for chemisorption between graphene and the underlaying metal. Indeed, for Ni(111), which is considered one of the metals belonging to the strong category, only a moderate adsorption energy of 67 meV per carbon atom has been recently evaluated on the basis of high-level many-body calculations (and up to 160 meV/C using semi-empirical forcefield corrections), which still is in the range of typical physisorption systems [11][12][13]. Therefore, it should be noted that the strong interaction mainly implies a strong hybridization between the graphene π states and the substrate, but is not necessarily reflected in the adsorption energies.…”