Authors: G P Papari and V M Fomin
Supercond. Sci. Technol. 32 105008
Abstract: We propose a mean-ﬁeld approach to describe the ﬂuxoid dependence of magnetoresistance oscillations measured on two YBa2Cu3O7−x (YBCO) nanorings. We unveil the relation between the quantum interference processes and current localization phenomena in superconductor nanorings, which are non-ideal because of the presence of stubs. The model, based on the change in supercurrent transmission due to ﬂuxoid dynamics, provides a dependence of the measured differential voltage on the external magnetic ﬁeld. In particular, the signature of the Little and Parks (LP) effect results from phase dynamics involving the transmission of probe currents crossing the ring, while magnetoresistance background is related to the screening currents dynamics driven by vortex nucleation. The model allows for tracing out the entire magnetoresistance, which is the result of the superposition of single vortex-like topological defects involving current localization. This approach provides a new conceptual frame to explain the LP effect that does not invoke the lowering of superconducting stiffness.