CURRENT PARTITION IN MULTIPROBE CONDUCTORS IN THE PRESENCE OF SLOWLY OSCILLATING EXTERNAL POTENTIALS

In the presence of a static potential drop a carrier stream incident a t a contact of the sample is partitioned into the other contacts accor ding to the transmission probabilities of the sample. The bare respons e to oscillating potentials, on the other hand, violates current conse rvation due to the piling up of unscreened charges in the sample, and has to be modified by taking the induced screening potential into acco unt. We present a novel derivation of the conductance response to osci llating external chemical potentials, find the response to an arbitrar y internal potential in terms of functional derivatives with respect t o the local potential of the scattering matrix of the conductor, and d etermine the screening potential for slowly oscillating potentials fro m the condition of local charge neutrality. We find that the current p artitioning depends on ratios of local densities of states which refle ct the injection and emission properties of the contacts of the sample .