Multipole modes and spin features in the Raman spectrum of nanoscopic quantum rings - art. no. 155304

We present a systematic study of ground state and spectroscopic properties of many-electron nanoscopic quantum rings. Addition energies at zero magnet ic field (B) and electrochemical potentials as a function of B are given fo r a ring hosting up to 24 electrons. We find discontinuities in the excitat ion energies of multipole spin and charge density modes, and a coupling bet ween the charge and spin density responses that allow to identify the forma tion of ferromagnetic ground states in narrow magnetic field regions. These effects can be observed in Raman experiments, and are related to the fract ional Abaronov-Bohm oscillations of the energy and of the persistent curren t in the ring.