Phase diagram and excitations of a Coulomb glass

This paper studies the phase diagram and the single-particle density of states of a lattice model of the Coulomb glass in three dimensions. For this purpose we calculate the free energy in the random phase approximation using the replica method to average over disorder. We find that the system has a transition to an antiferromagnetic phase below a critical disorder. Above the critical disorder the system has a glassy 'independent spin phase' at zero temperature which crosses over to paramagnetic phase as the temperature is increased. In the antiferromagnetic phase the single-particle excitation density has a feature, including the gap at the Fermi level due to long-range order. In the glassy phase we find the density of states (DOS) at nonzero temperatures and find that with temperature the DOS at the Fermi level increases faster than quadratically and the Coulomb gap decreases linearly. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.