Graphene–ferromagnet interfaces: hybridization, magnetization and charge transfer

Abstract

Electronic and magnetic properties of graphene-ferromagnet interfaces are investigated using first-principles electronic structure methods in which a single layer graphene is adsorbed on Ni(111) and Co(111) surfaces. Due to the symmetry matching and orbital overlap, the hybridization between graphene pπ and Ni (or Co) d(z(2)) states is very strong. This pd hybridization, which is both spin and k dependent, greatly affects the electronic and magnetic properties of the interface, resulting in a significantly reduced (by about 20% for Ni and 10% for Co) local magnetic moment of the top ferromagnetic layer at the interface and an induced spin polarization on the graphene layer. The calculated induced magnetic moment on the graphene layer agrees well with a recent experiment. In addition, a substantial charge transfer across the graphene-ferromagnet interfaces is observed. We also investigate the effects of thickness of the ferromagnet slab on the calculated electronic and magnetic properties of the interface. The strength of the pd hybridization and the thickness-dependent interfacial properties may be exploited to design structures with desirable magnetic and transport properties for spintronic applications.

Ferromagnetic order induced on graphene by Ni/Co proximity effects

“…Using Co and Ni interchangeably in this work is a good approximation as can be judged from detailed DFT calculations 19 . Nevertheless, there are some quantitative differences in the amount of charge transfer and the magnetic moment on the graphene mainly induced by slight changes in the bonding lengths both in the graphene and the interface layer involved.…”

Tunable induced magnetic moment and in-plane conductance of graphene in Ni/graphene/Ni nano-spin-valve-like structure: A first principles study

“…Many studies have attempted to fabricate graphene-based spintronic devices as new potential materials for magnetic tunneling junction (MTJ) applications. The Ni(111) surface is the most commonly used metal contact to study graphene-based spintronics owing to its structure similar to that of graphene (the smallest lattice mismatch among other transition metals) and its strong hybridization with graphene [7,16]. Recent experimental and theoretical studies of graphene in a sandwich structure with Ni(111) suggested two structural models: (i)Ni/graphene/Ni contact, where graphene is used as a bridge between two nickel electrodes and the current flow is parallel to the plane, and (ii)Ni/Graphene/Ni spin valve structure, which consists of two Ni slabs sandwiching a graphene layer and the current flows out of the plane.…”

First-principles investigation of the microscopic mechanism of the physical and chemical mixed adsorption of graphene on metal surfaces

“…There have been numerous experimental and theoretical studies on graphene contacted to metals such as Ni, Co, Ru, Rh, Pd, Ir, Pt and Cu. [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37] Experimental studies about the growth of graphene on metal close-packed surface such as Ni(111), Cu(111) and Ru(0001) rank rst. [38][39][40][41] Secondly, experimental studies about the growth of graphene on other low-index metal surfaces such as Ni(100), Rh(100) and Pt(110) have also been reported.…”

“…[42][43][44] However, theoretical studies on the interfaces between graphene and metals mainly focus on the metal close-packed surface such as Ni(111), Co(111), Cu(111) and so on. [28][29][30][31][32][33][34][35][36][37] In 2018, Mafra et al not only investigated different growth mechanisms of graphene on Ni(100), (110) and (111) surface by optical microscopy, Raman spectroscopy and optical transmission but also provided an atomistic model of the processes involved to support the experimental results by density functional theory calculations. 43 Theoretical studies on the adsorption of graphene on the (110) and (100) surfaces of other metals except Ni are rarely reported.…”