Shallow Coulomb gap and weak levellevel correlations in a deeply insulating electron system with interactions
Abstract
We consider a system of twodimensional electrons strongly localized by disorder. Interactions create a gap in the average tunneling density of states ν(E) at energies E close to the Fermi level. We derive a system of selfconsistent equations for the correlators of local densities of occupied and empty states. When either the interactions are screened by the gate or the temperature T is high enough, so that the Coulomb gap is shallow, the perturbative solution of the system yields analytical expressions for the interactioninduced correction δν(E) and the levellevel correlator. We show that even with shortrange interactions, δν(E) exhibits a singular energy dependence at T=0. We also demonstrate that at high T this energy dependence is a universal function of the the ratio E/T. Regarding the level correlations, we trace how the correlator falls off as a function of spatial and energy separation between the levels. We also trace how the correlations vanish with increasing T. Our most noticeable observation is that for two close energies the correlator changes sign from positive (attraction) at small distances to negative (repulsion) at large distances.
 Publication:

Physical Review B
 Pub Date:
 February 2001
 DOI:
 10.1103/PhysRevB.63.075304
 arXiv:
 arXiv:condmat/0004327
 Bibcode:
 2001PhRvB..63g5304B
 Keywords:

 73.21.b;
 71.23.An;
 71.55.Jv;
 Electron states and collective excitations in multilayers quantum wells mesoscopic and nanoscale systems;
 Theories and models;
 localized states;
 Disordered structures;
 amorphous and glassy solids;
 Condensed Matter  Mesoscale and Nanoscale Physics;
 Condensed Matter  Disordered Systems and Neural Networks;
 Condensed Matter  Strongly Correlated Electrons
 EPrint:
 14 pages