We considered the circulating current induced by the current magnification
and the persistent current induced by Aharonov-Casher flux. The persistent
currents have directional dependence on the direct current flow, but the
circulating currents have no directional dependence. Hence in the equilibrium,
only the persistent current can survives on the ring. For the charge current,
the persistent charge current cancelled between spin up and down states,
because of the time reversal symmetry of the Hamiltonian on the ring. So there
are only circulating charge currents on the ring for electrons with unpolarized
spin in the nonequilibrium. However, only the persistent spin currents
contributes to the spin currents for electrons with unpolarized spin.Comment: 9 pages and 4 ps figure
