Superconducting state evolution with applied magnetic flux in mesoscopic rings
Department of Physics, Shanghai University,
a e-mail: email@example.com
Received in final form: 28 September 2011
Published online: 21 November 2011
The magnetic flux dependence of the vortex state for small mesoscopic superconducting rings surrounded by a medium is investigated by the phenomenological Ginzburg-Landau theory. The influences of the ring size and the surface superconductivity on the free energy and total supercurrent are studied. For narrow rings, the persistent current evolves towards a periodic behaviour with magnetic flux. The complete paramagnetic or diamagnetic state, corresponding to positive or negative current flowing in the whole ring, can occur. A remarkable intermittent superconducting behaviour for the ground-state transition is found when the strength of surface-suppressed superconductivity is enlarged or the ring size is decreased. Consequently, a pure superconducting state with positive total current can be obtained.
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2011