title: Doping with Graphitic Nitrogen Triggers Ferromagnetism in Graphene.
abstract: Nitrogen doping opens possibilities for tailoring the electronic properties and band gap of graphene toward its applications, e.g., in spintronics and optoelectronics. One major obstacle is development of magnetically active N-doped graphene with spin-polarized conductive behavior. However, the effect of nitrogen on the magnetic properties of graphene has so far only been addressed theoretically, and triggering of magnetism through N-doping has not yet been proved experimentally, except for systems containing a high amount of oxygen and thus decreased conductivity. Here, we report the first example of ferromagnetic graphene achieved by controlled doping with graphitic, pyridinic, and chemisorbed nitrogen. The magnetic properties were found to depend strongly on both the nitrogen concentration and type of structural N-motifs generated in the host lattice. Graphenes doped below 5 at. % of nitrogen were nonmagnetic; however, once doped at 5.1 at. % of nitrogen, N-doped graphene exhibited transition to a ferromagnetic state at ∼69 K and displayed a saturation magnetization reaching 1.09 emu/g. Theoretical calculations were used to elucidate the effects of individual chemical forms of nitrogen on magnetic properties. Results showed that magnetic effects were triggered by graphitic nitrogen, whereas pyridinic and chemisorbed nitrogen contributed much less to the overall ferromagnetic ground state. Calculations further proved the existence of exchange coupling among the paramagnetic centers mediated by the conduction electrons.
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Piotr
authors.initials: P
authors.lastname: Błoński
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Tuček
authors.affiliation: Department of Inorganic Chemistry, University of Chemistry and Technology Prague , Technická 5, 166 28 Prague 6, Czech Republic.
authors.forename: Zdeněk
authors.initials: Z
authors.lastname: Sofer
authors.affiliation: Department of Inorganic Chemistry, University of Chemistry and Technology Prague , Technická 5, 166 28 Prague 6, Czech Republic.
authors.forename: Vlastimil
authors.initials: V
authors.lastname: Mazánek
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Martin
authors.initials: M
authors.lastname: Petr
authors.affiliation: Division of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , 637371 Singapore.
authors.forename: Martin
authors.identifier: 0000-0001-5846-2951
authors.initials: M
authors.lastname: Pumera
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Michal
authors.identifier: 0000-0002-1066-5677
authors.initials: M
authors.lastname: Otyepka
authors.affiliation: Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University in Olomouc , 17. listopadu 1192/12, 771 46 Olomouc, Czech Republic.
authors.forename: Radek
authors.identifier: 0000-0002-3147-2196
authors.initials: R
authors.lastname: Zbořil