Pseudo Jahn-Teller mechanism for symmetry-breaking phase transitions in vortex molecules

The phase transitions from a symmetric superconducting order parameter to a different or broken symmetry phase are investigated for thin mesoscopic superconductors well below the nucleation temperature. By using an effective two-state model the mechanism of these transitions has been revealed and four distinct types of transitions have been found. The symmetry-breaking phase transition has the same structure as the pseudo Jahn-Teller instability of high symmetry nuclear configurations in molecules. This analogy provides an interesting connection between real and vortex molecules. The existence of broken-symmetry phases is predicted to be strongly dependent on the size of the samples.status: publishe