title: Determination of the hyperfine magnetic field in magnetic carbon-based materials: DFT calculations and NMR experiments.
abstract: The prospect of carbon-based magnetic materials is of immense fundamental and practical importance, and information on atomic-scale features is required for a better understanding of the mechanisms leading to carbon magnetism. Here we report the first direct detection of the microscopic magnetic field produced at (13)C nuclei in a ferromagnetic carbon material by zero-field nuclear magnetic resonance (NMR). Electronic structure calculations carried out in nanosized model systems with different classes of structural defects show a similar range of magnetic field values (18-21 T) for all investigated systems, in agreement with the NMR experiments. Our results are strong evidence of the intrinsic nature of defect-induced magnetism in magnetic carbons and establish the magnitude of the hyperfine magnetic field created in the neighbourhood of the defects that lead to magnetic order in these materials.
authors.affiliation: Department of Physics, Federal University of Espírito Santo (UFES), Av. Fernando Ferrari, 514, 29075-910, Vitória, ES, Brazil.
authors.forename: Jair C C
authors.initials: JC
authors.lastname: Freitas
authors.affiliation: Department of Physics, Federal University of Espírito Santo (UFES), Av. Fernando Ferrari, 514, 29075-910, Vitória, ES, Brazil.|Department of Exact Sciences, Federal Fluminense University, 27255-250, Volta Redonda, RJ, Brazil.
authors.forename: Wanderlã L
authors.initials: WL
authors.lastname: Scopel
authors.affiliation: Department of Physics, Federal University of Espírito Santo (UFES), Av. Fernando Ferrari, 514, 29075-910, Vitória, ES, Brazil.
authors.forename: Wendel S
authors.initials: WS
authors.lastname: Paz
authors.affiliation: Department of Physics, Federal University of São Carlos (UFSCar), P.O. Box 676, 13565-905, São Carlos, SP, Brazil.
authors.forename: Leandro V
authors.initials: LV
authors.lastname: Bernardes
authors.affiliation: Department of Physics, Federal University of São Carlos (UFSCar), P.O. Box 676, 13565-905, São Carlos, SP, Brazil.
authors.forename: Francisco E
authors.initials: FE
authors.lastname: Cunha-Filho
authors.affiliation: Department of Physics, Federal University of São Carlos (UFSCar), P.O. Box 676, 13565-905, São Carlos, SP, Brazil.
authors.forename: Carlos
authors.initials: C
authors.lastname: Speglich
authors.affiliation: Department of Physics, Federal University of São Carlos (UFSCar), P.O. Box 676, 13565-905, São Carlos, SP, Brazil.
authors.forename: Fernando M
authors.initials: FM
authors.lastname: Araújo-Moreira
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia.
authors.forename: Damjan
authors.initials: D
authors.lastname: Pelc
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia.
authors.forename: Tonči
authors.initials: T
authors.lastname: Cvitanić
authors.affiliation: Department of Physics, Faculty of Science, University of Zagreb, Bijenička 32, HR-10000, Zagreb, Croatia.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Požek