Spin- and localization-induced fractional Aharonov-Bohm effect

We performed a theoretical analysis of the Aharonov-Bohm oscillations of the ground-state energy of quasi-one-dimensional quantum rings in a magnetic field, recently observed in conductance experiments, by means of quantum Monte Carlo calculations. The model rings considered contain $N=10\mathrm{}$ and $N=4\mathrm{}$ electrons, with radii of 20 and 120 nm, respectively. These parameters give a close description of the nanorings analyzed in the experiments. In particular, the two cases well reproduce the high- and low-electron-density regimes. For $N=10,$ we have found fractional Aharonov-Bohm effect with a period ${\Phi }_0/2\mathrm{}$ due to the changes in the total spin of the ground state. For $N=4,$ we have found fractional oscillations with a period ${\Phi }_0/4,$ which are shown to be a consequence of strong localization.