Critical point in the strong-field magnetotransport of a three-dimensional binary disordered composite medium

The electrical response of a three-dimensional composite medium composed of two isotropic conductors with charge carriers of the same sign is investigated. We consider such mixtures when subject to a strong magnetic field. First, an asymptotic analysis of a self-consistent effective medium approximation (SEMA) is applied for this purpose. A critical point in the behavior of the effective transverse Ohmic resistivity is predicted. At this critical point, occurring when the Hall resistivities of the two constituents are equal, the dependence of the induced magnetoresistance on the externally applied magnetic field changes from nonsaturating to saturating. The crossover between these distinct strong-field behaviors is characterized by a closed-form function of an appropriate scaling variable. An analogy is found between the investigated composite and a parallel-slabs composite. This provides physical insight into some of the results found using SEMA and indicates that their validity transcends that of SEMA. It also leads to some surprising predictions regarding the distributions of the local electric field and current density in the system.