Graphene–nickel interfaces: a review

Abstract

Graphene on nickel is a prototypical example of an interface between graphene and a strongly interacting metal, as well as a special case of a lattice matched system. The chemical interaction between graphene and nickel is due to hybridization of the metal d-electrons with the π-orbitals of graphene. This interaction causes a smaller separation between the nickel surface and graphene (0.21 nm) than the typical van der Waals gap-distance between graphitic layers (0.33 nm). Furthermore, the physical properties of graphene are significantly altered. Main differences are the opening of a band gap in the electronic structure and a shifting of the π-band by ∼2 eV below the Fermi-level. Experimental evidence suggests that the ferromagnetic nickel induces a magnetic moment in the carbon. Substrate induced geometric and electronic changes alter the phonon dispersion. As a consequence, monolayer graphene on nickel does not exhibit a Raman spectrum. In addition to reviewing these fundamental physical properties of graphene on Ni(111), we also discuss the formation and thermal stability of graphene and a surface-confined nickel-carbide. The fundamental growth mechanisms of graphene by chemical vapor deposition are also described. Different growth modes depending on the sample temperature have been identified in ultra high vacuum surface science studies. Finally, we give a brief summary for the synthesis of more complex graphene and graphitic structures using nickel as catalyst and point out some potential applications for graphene-nickel interfaces.

2D-MTJs: introducing 2D materials in magnetic tunnel junctions

“…However, the growth of graphene by catalytic CVD processes requires an in-depth investigation of the parameter space for each FM growth substrate. Whereas 2D materials grown by CVD on ferromagnets had already been envisaged (see for instance [46] in 1995), its in depth investigation had only recently begun [17,47,48]. In these studies, ferromagnetic catalysts were exposed to carbon-based molecules such as C 2 H 2 or C 2 H 4 , at conditions of temperature and pressure under which they dissociate on the surface.…”

Voltage-controlled inversion of tunnel magnetoresistance in epitaxial nickel/graphene/MgO/cobalt junctions

“…It thus turns out that, while a low-bias dip/gap is systematically present, its precise shape and width may vary from sample to sample. This can originate from variations in the degree of hybridization of graphene with Ni, which has a direct influence on the energy of the phonon modes [33,36]. Fluctuations in the degree of hybridization could also modify the relative contributions of the three conduction channels (, K, and M) to the overall spin polarized transport and be responsible for the fact that regimes A, B, and C do not seem to span exactly the same voltage ranges in the three samples considered in the present study.…”

Communication: Enhanced chemical reactivity of graphene on a Ni(111) substrate

“…[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] From the electronic point of view, the relatively strong interaction 20,30 between Ni(111) and graphene leads to hybridization between graphene π and Ni 3d orbitals, resulting in band-gap opening. 20,23,35,36 Coherently with π states hybridization, charge redistribution occurs, implying electron accumulation close to the G surface.…”