Magnetoresistance of carbon nanomaterials

This paper contains an analysis of published experimental data on the magnetoresi stance in the region of Mott hopping conduction in various carbon materials whose properties are determined by nanoscale inhomogeneities. The validity of the mechanism of shrinkage of a localized state in a magnetic field and the spin polarization mechanism involving the spin-dependent contribution of hopping over doubly occupied electronic states is considered. A simple analytic model is proposed for the spin polarization mechanism. An expression for magnetoresi stance in a weak magnetic field is derived within the proposed model. It is demonstrated that only a combined effect of the spin-polarization mechanism and wave function shrinkage is capable of providing an adequate description of the magnetoresi stance of carbon nanomaterials. Promising areas to search for objects with high magnetoresi stance among the materials of this class are discussed.