Spin-polarized electronic/transport properties of iron-benzene complex-adsorbed graphene sheets

Abstract

The electronic and transport properties of a series of covalently functionalized graphene sheets m(FeBz)n-G (m, n = 1, 2) are calculated by density functional theory (DFT) and the nonequilibrium Green's function (NEGF) methods. All the studied systems are chemically stable due to the d–π interaction between Fe and graphene. Addition of (FeBz)n (n = 1, 2) introduces a half-metallic behavior: the up-spin state degradates into a semiconductor channel while the down-spin state behaves as a metallic channel. Particularly, two-fold anisotropy magnetism could be obtained, with the ferromagnetic ordering extending either parallel to the graphene plane originated from the Fe-d up-spin state or perpendicular due to the d-electron coupling along the Fe-Bz-Fe-Bz chain in the down-spin state. Because of the trapping effect, attaching (FeBz)n decreases the conductivity. Anisotropy inherited from graphene after functionalized with (FeBz)n (n = 1, 2): zigzag direction has higher conductivity than armchair direction. The number and alignment style of (FeBz)n (n = 1, 2), and the spin-polarized character, all have impacts on the transport property. Our findings provide useful guidelines for achieving graphene-based electronic and spintronic nanodevices by attaching other similar long multi-decker metal-arene systems.