Aharonov–Bohm/Casher effect in a Kondo ring

Abstract

The influence of a magnetic impurity or ultrasmall quantum dot on the spin and charge persistent currents of a mesoscopic ring is investigated. The system consists of electrons in a one-dimensional ring threaded by spin-dependent Aharonov–Bohm/Casher fluxes, and coupled via an antiferromagnetic exchange interaction to a localized electron. The problem is mapped onto a Kondo model for the even-parity channel plus free electrons in the odd-parity channel. The twisted boundary conditions representing the fluxes couple states of opposite parity unless the twist angles φ α satisfy φ α = f α π, where f α are integers, with spin index α=↑, ↓ . For these special values of φ α , the model is solvable by the Bethe ansatz.