Electric-field-dependent variable-range hopping conductance in quasi-two-dimensional systems: Application to PrBa2Cu3O7-y-based superconductor–normal-metal–superconductor junctions

The author has the right to post and update the article on a free-access e-print server using files prepared and formatted by the author. Any such posting made or updated after acceptance of the article for publication by APS should include a link to the online APS journal article abstract. In all cases, the appropriate bibliographic citation and notice of the APS copyright must be included.We have calculated the hopping conductivity of quasi-two-dimensional systems by using the variable-range hopping conduction mechanism in the presence of an electric field. We considered that the localized states are randomly distributed both in energy and space coordinates. Localized carriers hop from one state to another in both coordinates. We also considered that at a particular temperature the localized carriers are distributed according to the Fermi distribution function both below and above the Fermi level. The expression of the conductivity for the constant density of states was calculated. After some approximations, the expression of the conductivity was shown to reduce to expressions found in the literature. We also compared our theory with experimental results of PrBa2Cu3O7-y based S/N/S junctions. Good agreement between theory and experiment was found.Natural Sciences and Engineering Research Council of Canada (NSERC