We have studied the ac response and magnetoresistance of a two-dimensional electron gas in high-mobility samples in the presence of smooth disorder, with emphasis on the composite-fermion description of a half-filled Landau level. We have found that the low-$\omega$ behavior of the ac conductivity $\sigma(\omega)$ is governed by memory effects associated with return processes that are neglected in Boltzmann transport theory: the return-induced correction to $\mathrm{Re} \sigma$ exhibits a kink $\propto|\omega|$. It is shown that the non-Markovian quasiclassical kinetics leads to a strong magnetoresistance $\Delta\rho_{xx}$. We argue that the quasiclassical memory effects account for the positive $\Delta\rho_{xx}$ observed at small deviations from half-filling. At a larger deviation, the positive magnetoresistance is followed by a sharp falloff of $\rho_{xx}$.

TY JOUR
TI Quasiclassical memory effects: anomalous transport properties of two-dimensional electrons and composite fermions subject to a long-range disorder
AU Evers, F.
AU Mirlin, A. D.
AU Polyakov, D. G.
AU Wölfle, P.
PB Успехи физических наук
PY 2001
JO Успехи физических наук
JF Успехи физических наук
JA Усп. физ. наук
VL 171
IS 13
SP 27-31
UR https://ufn.ru/ru/articles/2001/13/d/
ER https://doi.org/10.1070/1063-7869/44/10S/S04