Two-dimensional (2D) materials have unique properties making them highly-valued potential candidates for spintronics devices. However, there are several challenges to be overcome to realise them. For instance, most 2D materials are not ferromagnetic (FM). Therefore, they require special spin injection approaches, which could be difficult due to their reduced thicknesses.

We have measured the induced magnetic moment in rotated-domain graphene as a result of the proximity effect in the vicinity of FM substrates with element-specific X-ray magnetic circular dichroism (XMCD) measurements at the Carbon K-edge and applied as a first the sum rules to extract the orbital and spin-magnetic moment contributions. Furthermore, polarised neutron reflectivity (PNR) experiments were carried out to determine the magnitude of the induced magnetic moment and its dependence on epitaxy and magnetic moment amplitude. Although a higher magnetic moment was expected to be induced in the epitaxial graphene sample, the PNR results indicate that the epitaxial graphene film had a  magnetic moment of ∼0.41 μ_B/C atom on Ni(111) compared to ∼0.49 μ_B/C on Co(0001). Both values are higher than those predicted in other experimental or computational studies. PNR measurements on paramagnetic graphene/Ni₉Mo(111) support the model where the induced magnetic moment in graphene arises due to the opening of the graphene’s Dirac cone as a result of the strong Carbon p_Z- transition metal Ferromagnet 3d hybridization as shown in Figure 1. These results provide the first quantitative estimation of the induced magnetization in a 2D material such as graphene and paves the way not only to a better understanding between interlayer coupling but also to apply these techniques to other 2D materials.

Figure Caption: (a) Schematic of the effect of the induced polarisation on the opening of the graphene’s Dirac cone and measurement geometry for PNR experiments with the coloured arrows indicating the polarisation of the neutrons. XMCD  (b) spectra for the graphene layer at the Carbon K-edge. PNR Fresnel reflectivities at 300 K (c) and (d) the nuclear scattering length density profile (upper panel) and the magnetic scattering length density profile (lower panel) as provided by the best fit to the data.