ENHANCEMENT OF PERSISTENT CURRENTS BY HUBBARD INTERACTIONS IN DISORDERED 1D RINGS - AVOIDED LEVEL-CROSSINGS INTERPRETATION

We study effects of local electron interactions on the persistent curr ent of one dimensional disordered rings. For different realizations of disorder we compute the ensemble average current as a function of Aha ronov-Bohm flux to zeroth and first orders in the Hubbard interaction. We find that the persistent current is enhanced by on site interactio ns. Using an avoided level crossings approach, we derive analytic form ulas which explain the numerical results at weak disorder. The same ap proach also explains the opposite effect (suppression) found for spinl ess fermion models with intersite interactions.