COULOMB DRAG IN SYSTEMS WITH TUNNELING BRIDGES

We study the Coulomb drag effect in double layer electronic systems wi th local tunneling links. The possibility of tunneling between the lay ers leads to a pronounced exchange contribution to the transconductanc e, which is negative and nonvanishing at zero temperature. The diffusi ve motion of the electrons inside each layer in interplay with the ele ctron-electron interaction causes a distinct singular temperature depe ndence of the transconductance at low temperatures.