Synthesis and characterization of stable room temperature bulk ferromagnetic graphite

Magnetic Particle Imaging Using Ferromagnetic Magnetization

“…Ferromagnetic carbon can be produced by a vapor phase redox reaction in closed nitrogen atmosphere with copper oxide (CuO) [2,3]. Recent theoretical and experimental reports confirm that magnetic carbon is originated from defects [6][7][8][9].…”

“…To compare MPI results for superparamagnetic versus ferromagnetic nanofluids, parameters from [12] are adopted: For the superparamagnetic nanofluid, the saturation magnetization is M s =477x10 3 A/m and a=505.06 A/m. Those values are used for the ferromagnetic nanofluid too and, in addition, the following values to form an adequate hysteresis curve: Figure 2 shows the MPI signal chain for superparamagnetic and ferromagnetic particles for various values of the offset field: Magnetization, induced voltage, and frequency spectrum.…”

Influence of iron impurities on defected graphene

“…Later, graphite [3][4][5][6][7][8] and especially graphene [9,10] have been the focus of research in the pursuit of new materials with advanced properties, particularly referred to electronic properties, such as magnetism and electronic transport, in close relationship with structural features like defects and quantum confinement.…”

“…Although magnetism in carbon materials has been a matter of controversy a few years ago, there were many articles reporting about this field [3,4,[11][12][13][14] until this phenomenon was unambiguously demonstrated [15]. Recently, some studies have undertaken the attempt to explain theoretically this phenomenon [16][17][18][19][20][21][22][23][24][25][26], being the origin of this behavior the existence of unpaired electrons, which could arise from defects, impurities and other local structural perturbations.…”

“…Although for some configurations the stability of multivacancies could be low and coalescence could happen, it is important not to forget that in normal samples, iron is present in the specimen before the defect is created -either using a sophisticated method such as irradiation [28] or through a simpler and less controlled technique, as the redox etching [3,4]. The iron impurities such as atoms or clusters are already in the specimen and available to interact with the vacancy as soon as it is created, thus increasing the probability of the embedding of iron cluster (or atom) in the vacant graphene to occur.…”