ALTERNATE SIGN REVERSAL IN MAGNETIC FLUX-INDUCED PERSISTENT CURRENT IN AN ISOLATED MESOSCOPIC RING BY HALF-THE-RING ELECTROSTATIC POTENTIAL

We calculate the energy spectrum for an electron in an isolated ideal one-dimensional mesoscopic ring subject to magnetic flux threading the ring and electrostatic potential applied to one half of the ring. The problem is reduced to that of Kronig-Penney potential with Beyers and Yang boundary condition around the ring. The band E is periodic in ma gnetic phase shift theta and approximately periodic in electrostatic p hase shift phi. At low electrostatic potential, E(theta) bands are shi fted in half the potential. Where the E(theta) bands are degenerate, b and gaps are formed by electrostatic potential. Above some critical st rength of electrostatic potential narrow energy bands with wide gap ar e formed that are propagating in one half of the ring and decaying in the other half. From the E(theta) band magnetic-flux-induced persisten t current is calculated. Possibility of its alternate sign reversal by increasing the strength of the electrostatic potential is discussed.