Kinetics and localization of composite fermions in a random magnetic field

We develop a theoretical description of the disordered composite-fermion (C F) metal, which shows that the Drude-like picture of the CF kinetics is onl y marginally valid at nu = 1/2 and becomes totally inadequate at small (\nu - 1/2\ << 1) deviations from half-filling. We argue that the major effect of disorder is the quasiclassical localization of CFs in a random magnetic field (RMF) and discuss its implications for transport measurements. We stu dy the transport properties of fermions in a smoothly varying RMF with mean (B) over bar. We calculate the conductivity at strong disorder and zero B, when the transport is governed by percolating 'snake states'. We demonstra te that at high (B) over bar the conductivity is due to the exponentially w eak non-adiabatic scattering processes. We argue that the classical localiz ation yields a strong enhancement of the magnetooscillations. (C) 1998 Else vier Science B.V. All rights reserved.