Possible ferro-electro-magnetic behaviours of graphene-based materials: hydrogenated graphene, MWCNTs and reduced graphene-oxide (GO)

Abstract

This study investigated the electric polarization and magnetic behaviours of various graphene-based materials, including hydrogenated graphene (H-graphene), multi-wall carbon nanotubes (MWCNTs), and reduced graphene oxide (r-GO). Results showed that MWCNTs exhibit higher magnetization, with a magnetic squareness (M_r/M_s) of approximately ≈0.5, compared to H-graphene (≈0.25). H-graphene exhibits the highest electric polarization compared to MWCNTs/r-GO, whereas r-GO demonstrates the lowest levels of polarization and magnetization compared to H-graphene/MWCNTs. The valence band maximum (4.08 eV for MWCNTs, 4.26 eV for H-graphene, and 4.78 eV for r-GO) in quasi-localized states at the Fermi level results in defects in the graphene-based lattice, which are associated with dipole moment and lead to alterations in magnetic behaviours. Different density of states (DOS) is attributed from the ultra-violet photoelectron spectra and the small variations in the Fermi edge is observed in H-graphene, MWCNTs, and r-GO are responsible for the observed magnetisation and polarizations. The unique polarization/magnetization behaviours present an opportunity for potential exploitation in storage and information processing technologies in the science and engineering community.