Superconducting fluctuations in a mesoscopic ring structure. Little-Parks oscillation in fluctuation regime

Superconducting fluctuation in a mesoscopic superconducting ring is studied and its effect on the Little-Parks oscillation is discussed. We introduce Ginzburg-Landau type effective action to describe the fluctuation of the or der parameter and treat the nonlinear term by Hartree-Fock approximation. I t is shown that the strength of the superconducting fluctuation varies as a function of the magnetic flux enclosed in the ring. This phenomenon is exp ected to be responsible for the experimentally observed reduction of the am plitude of Little-Parks oscillation. (C) 2001 Elsevier Science B.V. All rig hts reserved.