Influence of spin on the persistent current of strongly interacting electrons

The lowest eigenenergies of a few, strongly interacting electrons in a one-dimensional ring are studied in the presence of an impurity barrier. The persistent current I, periodic in an Aharonov-Bohm flux penetrating the ring, is strongly influenced by the electron spin. The impurity does not remove discontinuities in I at zero temperature. The total electron spin of the ground state oscillates with the flux. Strong electron-electron interaction enhances I, albeit not up to the value of the clean ring which itself is smaller than I for free electrons. I disappears on a temperature scale that depends exponentially on the electron density. In the limit of very strong interaction, the response to small fluxes is diamagnetic.