In this paper, we use the coherent potential approximation to study the role quantum hopping plays on the Coulomb gap of insulating strongly correlated d=2 and d=3 dimensional systems. We find that substantial increase in the density of states at the Coulomb gap occurs only when the ratio between the hopping integral t and the gap width B exceeds a critical value. We estimate that the hopping integral corresponding to the experimental condition n<nc/3 satisfies t/B<0.05. For such values of t/B, quantum hopping brings about little change in the single particle density of states. The classical Coulomb gap therefore remains intact in both three and two dimensional systems, in contrast to a previous claim that the gap disappears for d=2 systems. The implication of these results on experiments on doped semiconductors is discussed.
ASJC Scopus subject areas
- Condensed Matter Physics