Novel Transport Mechanism for Interacting Electrons in Disordered Systems: Variable-Range Resonant Tunneling

Recent experiments on the quantum Hall effect [1,2] and on the hopping transport in 2D Si MOSFETs [3] and delta-doped GaAs/AlGaAs heterostructures [4] show that prefactor so in the exponential temperature dependence of the hopping conductivity has, under certain conditions, a universal form (e/h)f(T/T0) with f ≈1 at T ≈ T0. Aleiner et al. [5] have remarked that such an effect can be due to hopping via electron-electron scattering, as considered by Fleishman et al. [6], rather than via conventional electronphonon scattering. We suggest below an alternative to this mechanism based on non-Hubbard Coulomb correlations which can account for the observed effects. To interpret phononless hopping evidenced by experimental observations, it is necessary to take into account electron-electron interactions, though such interactions can also play an important role for phonon-assisted hopping. The role of non-Hubbard Coulomb correlations for the low-temperature hopping conduction was first pointed out by Knotek and Pollak [7]. They considered