CONDUCTANCE FLUCTUATIONS AND DISTRIBUTION IN DISORDERED CHAINS IN THEPRESENCE OF AN ELECTRIC-FIELD

A simple Kronig-Penney model for 1D mesoscopic systems with disordered delta-peak and finite width potentials is used to study numerically t he influence of a constant electric field on the conductance fluctuati ons and probability distribution. The electric field applied to such s ystems allows us to obtain the insulating, transition and metallic reg imes. The results are globally in agreement with the previous works on quasi-1D and higher dimensions. However, the following new behaviors are observed in such systems: (a) For the superlocalisation observed r ecently in such systems, the conductance fluctuations are very small i n comparison to the usual insulating regime. (b) The transition region does not correspond to that expected by Mate and Care for (E similar or equal to V). This region is found to be still an insulating one. By increasing the field we find a behavior different from the well-known one in this region. (c) In some regions of the metallic regime the co nductance decreases instead of increasing with the field due to the Wa nnier-Stark ladder localization observed recently in such systems. Fur ther, discussions are given about the effect of the held on the dielec tric rupture and also on the insulator-metal transition.