SUPPRESSION OF LEVEL HYBRIDIZATION DUE TO COULOMB INTERACTIONS

We investigate an ensemble of systems formed by a ring enclosing a mag netic Bur. The ring is coupled to a side stub via a tunnelling junctio n and via Coulomb interaction. We generalize the notion of level hybri dization due to the hopping, which is naturally defined only for one-p article problems, to the many-particle case, and we discuss the compet ition between the level hybridization and the Coulomb interaction. It is shown that strong enough Coulomb interactions can isolate the ring from the stub, thereby increasing the persistent current. Our model de scribes a strictly canonical system (the number of carriers is the sam e for all ensemble members). Nevertheless for small Coulomb interactio ns and a long side stub the model exhibits a persistent current typica lly associated with a grand canonical ensemble of rings and only if th e Coulomb interactions are sufficiently strong does the model exhibit a persistent current which one expects from a canonical ensemble.