Fluctuation persistent current in small superconducting rings

Abstract

We extend previous theoretical studies of the contribution of fluctuating Cooper pairs to the persistent current in superconducting rings subjected to a magnetic field. For sufficiently small rings, in which the coherence length $\xi$ exceeds the radius $R$, mean field theory predicts the emergence of a flux-tuned quantum critical point separating metallic and superconducting phases near half-integer flux through the ring. For larger rings with $R\gtrsim \xi$, the transition temperature is periodically reduced, but superconductivity prevails at very low temperatures. We calculate the fluctuation persistent current in different regions of the metallic phase for both types of rings. Particular attention is devoted to the interplay of the angular momentum modes of the fluctuating order parameter field. We discuss the possibility of using a combination of different pair-breaking mechanisms to simplify the observation of the flux-tuned transition in rings with $\xi >R$.

16 pages, 8 figures

References in corpus (6)

• Fluctuation Superconductivity in Mesoscopic Aluminum Rings
• h/e-Periodicity in Superconducting Loops
• Emergence of $h/e$-period oscillations in the critical temperature of small superconducting rings threaded by magnetic flux
• Microscopic analysis of the superconducting quantum critical point: Finite temperature crossovers in transport near a pair-breaking quantum phase transition
• Fluctuation conductivity of thin films and nanowires near a parallel-field-tuned superconducting quantum phase transition
• Pair-breaking effect on mesoscopic persistent currents

Cited by in corpus (21)

• Nontopological zero-bias peaks in full-shell nanowires induced by flux tunable Andreev states
• Signatures of topological phase transitions in mesoscopic superconducting rings
• Even-odd effect and Majorana states in full-shell nanowires
• Asymmetric Little-Parks Oscillations in Full Shell Double Nanowires
• Theory of Caroli-de Gennes-Matricon analogs in full-shell hybrid nanowires
• Phenomenology of Majorana zero modes in full-shell hybrid nanowires
• Fluxoid-induced pairing suppression and near-zero modes in quantum dots coupled to full-shell nanowires
• Manipulating superconducting fluctuations by the Little-Parks-de Gennes effect in ultrasmall Al loops
• Josephson effect and critical currents in trivial and topological full-shell hybrid nanowires
• Absence of Majorana oscillations in finite-length full-shell hybrid nanowires
• Little-Parks oscillations near a persistent current loop
• Subgap transport in superconductor--semiconductor hybrid islands: Weak and strong coupling regimes
• Fluctuation conductivity of disordered superconductors in magnetic fields
• Fluxoid valve effect in full-shell nanowire Josephson junctions
• Anomalous mesoscopic kinetics in disordered superconductors
• Proximity-induced minimum radius of superconducting thin rings closed by the Josephson 0 or pi junction
• Normal persistent currents in proximity-effect bilayers
• Phase slip statistics of a single isolated flux-biased superconducting ring
• Fluctuations in a mesoscopic superconducting ring: resonant behavior of conductivity and specific heat in two mode critical regime
• Absence of Quasi-Majorana False Positives in Full-Shell Hybrid Nanowires
• Fluxoid solitons in superconducting tapered tubes and bottlenecks