Realization of ferromagnetic graphene oxide with high magnetization by doping graphene oxide with nitrogen

Abstract

The long spin diffusion length makes graphene very attractive for novel spintronic devices, and thus has triggered a quest for integrating the charge and spin degrees of freedom. However, ideal graphene is intrinsic non-magnetic, due to a delocalized π bonding network. Therefore, synthesis of ferromagnetic graphene or its derivatives with high magnetization is urgent due to both fundamental and technological importance. Here we report that N-doping can be an effective route to obtain a very high magnetization of ca. 1.66 emu/g, and can make graphene oxide (GO) to be ferromagnetism with a Curie-temperature of 100.2 K. Clearly, our findings can offer the easy realization of ferromagnetic GO with high magnetization, therefore, push the way for potential applications in spintronic devices.

Tuning the Electronic and Magnetic Properties of Nitrogen-Functionalized Few-Layered Graphene Nanoflakes

“…46 The * resonance peak at 397.7 eV, attributed to pyridine-like bonding, arises due to transitions from the K-shell (N 1s) to the unoccupied * orbital. 48,49 The peak position of the pyridine like species is however 1.0 eV lower to that reported by Liu et al in the case of nitrogen doped graphene oxide 21,47 and that by Usachov et al in their study of N-graphene synthesised from s-triazine molecules. 44 Comparing the deconvoluted N K-edge spectra of the N-functionalised samples (Figs 2(c, d)), the most significant difference observed is the peak III (attributed to pyrrolic nitrogen), thus indicating higher pyrrolelike bonding for FLG:N (PECVD) samples.…”

“…Indeed, Liu et al 21 have observed high values of magnetization in ferromagnetic graphene oxide (GO), when doped with nitrogen. The substitution by nitrogen of a carbon atom in the graphene lattice leads to an increase in the electronic density of states and the nitrogen dopant can provide -electron close to the Fermi level of graphene, thereby enhancing the coupling via a reduction in the magnetic moment distance.…”

“…The substitution by nitrogen of a carbon atom in the graphene lattice leads to an increase in the electronic density of states and the nitrogen dopant can provide -electron close to the Fermi level of graphene, thereby enhancing the coupling via a reduction in the magnetic moment distance. 21,22 Zhang et al 19 proposed that the combination of vacancy defects and N atoms may provide a unique way for enhancing the magnetic moment of graphene. However, experimental evidence from nitrogen-doped graphene for such magnetism remains both scarce and controversial.…”

“…The substitution by nitrogen of a carbon atom in the graphene lattice leads to an increase in the electronic density of states and the nitrogen dopant can provide -electron close to the Fermi level of graphene, thereby enhancing the coupling via a reduction in the magnetic moment distance. 21,22 Zhang et al 4 characterised using X-ray absorption near edge spectroscopy (XANES), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy techniques to understand the changes in the electronic and bonding structure. Magnetic property measurements were carried out using a SQUID type magnetometer in conjunction with Magnetic Force Microscopy (MFM), which revealed higher ferromagnetic magnetisation saturation values of the ECR samples (118.62 x 10 -4 emu/gm), as compared to rf-PECVD samples (0.39 x 10 -4 emu/gm) and the pristine samples (3.47 x 10 -4 emu/gm), respectively.…”

“…[15][16][17][18][19][20][21] The nitrogen atom, containing one additional electron, upon replacing the carbon in the graphene lattice 15 , can introduce novel electronic properties as well as magnetic moment into graphene. 16 These localized magnetic moments are induced by various arrangements of the N atom, with the pyridine and pyrrole like N-doping defects breaking the degeneracy of the spin polarisation of graphene. …”