Coulomb glasses: A comparison between mean field and Monte Carlo results

Article

关键词: DISORDERED-SYSTEMS;    ELECTRON GLASS;    CONDUCTIVITY;    GAP;   

DOI  :  10.1103/PhysRevB.85.155206

来源: SCIE

【 摘 要 】

Recently a local mean field theory for both eqiulibrium and transport properties of the Coulomb glass was proposed [Amir et al., Phys. Rev. B 77, 165207 (2008); 80, 245214 (2009)]. We compare the predictions of this theory to the results of dynamic Monte Carlo simulations. In a thermal equilibrium state we compare the density of states and the occupation probabilities. We also study the transition rates between different states and find that the mean field rates used in the aforementioned papers underestimate a certain class of important transitions. We propose modified rates to be used in the mean field approach which take into account correlations at the minimal level in the sense that transitions are only to take place from an occupied to an empty site. We show that this modification accounts for most of the difference between the mean field and Monte Carlo rates. The linear response conductance is shown to exhibit the Efros-Shklovskii behavior in both the mean field and Monte Carlo approaches, but the local mean field method strongly underestimates the current at low temperatures. When using the modified rates better agreement is achieved.

【 授权许可】

Free