CORRELATION-EFFECTS IN DOUBLE-QUANTUM-WELL SYSTEMS

An interacting double-layer electron system, with uniform positive bac kgrounds, is considered at finite temperatures and in the presence of a strong perpendicular magnetic field for integer filling factors. The low-energy physics of this system is described using an effective act ion formalism. The density-density correlation functions and the long- wavelength collective excitations of the electronic system (magnetopla smons) are obtained. The results are valid beyond the random-phase app roximation. Finally, the response of the system to electromagnetic int eractions is considered and the current induced in one layer (transcon ductivity), when a current is driven only through the other layer, is evaluated. All results take into account explicitly interlayer and int ralayer correlations.