Information on atomic-scale features is required for a better understanding of the mechanisms leading to magnetism in non-metallic, carbon-based materials. This work reports a direct evaluation of the hyperfine magnetic field produced at 13C nuclei in ferromagnetic graphite by nuclear magnetic resonance (NMR). The experimental investigation was made possible by the results of first-principles calculations carried out in model systems, including graphene sheets with atomic vacancies and graphite nanoribbons with edge sites partially passivated by oxygen. A similar range of maximum hyperfine magnetic field values (18-21T) was found for all systems, setting the frequency span to be investigated in the NMR experiments; accordingly, a significant 13C NMR signal was detected close to this range without any external applied magnetic field in ferromagnetic graphite.
@article{arxiv.1406.1119,
title = {Hyperfine magnetic field in ferromagnetic graphite},
author = {Jair C. C. Freitas and Wanderlã L. Scopel and Wendel S. Paz and Leandro V. Bernardes and Francisco E. Cunha-Filho and Carlos Speglich and Fernando M. Araújo-Moreira and Damjan Pelc and Tonči Cvitanić and Miroslav Požek},
journal= {arXiv preprint arXiv:1406.1119},
year = {2019}
}