Geometric Effect On The Phase Transition In Mesoscopic Loops Threaded By An Aharonov-Bohm Flux

The quantum phase transition in mesoscopic noncircular loops threaded by an Aharonov-Bohm flux is systematically investigated by numerically solving the Bogoliubov-de Gennes equations self-consistently. We focus on the magnetic flux dependence of the s-wave superconducting order parameter and current in symmetric and asymmetric samples. The influence of surface indentation or bulge defects positioned at the inner or outer edge of the sample on the periodic oscillation is also discussed. We find various hc/e-flux periodicity evolution patterns, and the periodic phase transitions between the superconducing state and the resistive/normal state are demonstrated besides the superconducing state transitions. Our investigation may shed new light on material engineering and provide important insights to designing superconducting quantum devices. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4742051]