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Charge transfer and hybridization effect at the graphene-nickel interface: A tight binding model study

Sahu, Sivabrata, Sahoo, Mihir Ranjan, Kushwaha, Anoop Kumar, Rout, G.C., Nayak, S.K.
Carbon 2019 v.142 pp. 685-696
electrons, graphene, hybridization, magnetic properties, magnetism, models, nickel, temperature
We have investigated here, the electronic and magnetic properties of graphene–nickel system by tight-binding mean-field approach. Strong hybridization between the 2pz orbital of graphene and 3dz2 orbital of nickel occurs when monolayer graphene is placed over a single layer of ferromagnetically ordered Ni (111) metal due to the excellent lattice matching between the two layers. This hybridization greatly affects the electronic and magnetic properties of the bilayer system, resulting in a significantly reduced local magnetic moment of the nickel layer and an enhanced induced spin polarization on the graphene layer. The calculated Hamiltonian revealed critical information regarding the first-, second-and third-nearest-neighbour hopping integrals of π− electrons of graphene besides the Coulomb correlation of electrons in nickel (111). The Hubbard type Coulomb interactions present in nickel lattices were treated within the mean-field approximation. Zubarev's technique was employed to calculate electronic Green's functions and subsequent investigation of the temperature dependent ferromagnetic magnetization of nickel (111)was carried out through self-consistent calculation. Further calculations regarding the induced magnetization in the graphene, total magnetization in bilayer layer system, electronic band dispersion, spin resolved density of states (DOS) and spin polarization efficiency have been carried out. The results were corroborated by experimental observations.