Abstract:
The negative magnetoresistance effect (NME) observed in quasi-two-dimensional graphite layers on the surface of which islands-nuclei of vertical graphene (VGN) with a high density of paramagnetic defects (PMC) with uncompensated spins were formed is investigated. A hypothesis is proposed for a possible reason for the NME observation, which is formally described by the theory of quantum corrections to the Drude conductivity with the orientation of the magnetic field perpendicular to the plane of the layer. The model is based on the assumption that the magnetic flux $\Phi$ is distributed non-uniformly along the plane of the C-layer due to the fact that the islands of the VGN phase contain a high density of PMC with uncompensated spins. Ferromagnetic regions are induced in the vicinity of the PMC clusters due to the parallel alignment of spins on the PMC due to the exchange interaction. It is assumed that the described redistribution of the magnetic
flux $\Phi$ should lead to its concentration in the regions of the location of the islands-nuclei of the VGN phase and its strong weakening (rarefaction) between the islands. This explains the apparent observation of the OMR effect described by the theory of quantum corrections at high values of the external magnetic field B given by the superconducting solenoid (up to 8 T), although in reality the greater part of the conducting C-layer is actually in a strongly weakened field.
Keywords:quantum corrections to conductivity, weak localization, negative magnetoresistive effect, vertical graphene, carbon nanostructure, magnetism in carbon structures.
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