Aharonov-Bohm/Casher effect in a Kondo ring

The influence of a magnetic impurity or ultrasmall quantum dot on the spin and charge persistent currents of a mesoscopic ring is investigated. The sy stem consists of electrons in a one-dimensional ring threaded by spin-depen dent Aharonov-Bohm/Casher fluxes, and coupled via an antiferromagnetic exch ange interaction to a localized electron. The problem is mapped onto a Kond o model for the even-parity channel plus free electrons in the odd-parity c hannel. The twisted boundary conditions representing the fluxes couple stat es of opposite parity unless the twist angles phi(alpha) satisfy phi(alpha) =f(alpha)pi, where f(alpha) are integers, with spin index alpha = up arrow , down arrow. For these special values of phi(alpha), the model is solvable by the Bethe ansatz. (C) 2000 Elsevier Science B.V. All rights reserved.