THE AC MAGNETORESISTANCE IN INHOMOGENEOUS SOLIDS

The theory of AC magnetoresistance in inhomogeneous solids is developed using the effective-medium theory. Calculations are performed for systems which consist of random high- and low-conductivity regions. The weak magnetic field H is directed along the z axis. The effective conductivity changes DELTAsigma(m)xx and DELTAsigma(m)zz and the magnetoresistances DELTArho(m)xx and DELTArho(m)zz in both the low- and the high-frequency regions are calculated up to the H-2 approximation. The calculations show that, owing to inhomogeneities, plateaux of the finite values DELTAsigma(m)zz and DELTArho(m)zz in the low-frequency region occur. It is possible to have both DELTArho(m)xx > DELTArho(m)zz. In the high-frequency limit the equalities DELTAsigma(m)zz = DELTArho(m)zz = 0 hold as in homogeneous solids.