ORDERING EFFECT OF COULOMB INTERACTION IN BALLISTIC DOUBLE-RING SYSTEMS

We study a model of two concentric onedimensional rings with incommens urate areas A(1) and A(2), in a constant magnetic field. The two rings are coupled by an nonhomogeneous inter-ring tunneling amplitude, whic h makes the one-particle spectrum chaotic. For noninteracting particle s the energy of the many-body ground state and the first excited state exhibit random fluctuations characterized by the Winger-Dyson statist ics. In contrast, we show that the electron-electron interaction order s the magnetic field dependence of these quantities, forcing them to b ecome periodic functions, with period proportional to 1/(A(1) + A(2)). In such a strongly correlated system the only possible source of diso rder comes from charge fluctuations, which can be controlled by a tuna ble inter-ring gate voltage. (C) 1997 Published by Elsevier Science Lt d.