Universal Mechanism for Breaking the hc/2e Periodicity of Flux-Induced Oscillations in Small Superconducting Rings

Victor Vakaryuk

doi:10.1103/PhysRevLett.101.167002

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Universal Mechanism for Breaking the hc/2e Periodicity of Flux-Induced Oscillations in Small Superconducting Rings

Victor Vakaryuk

DOI 10.1103/PhysRevLett.101.167002 · Physical Review Letters

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Abstract

A universal mechanism of restoration of minimal hc/e periodicity in the response of small superconducting rings or cylinders to the magnetic flux is proposed. The mechanism is based on the dependence of the Cooper pair’s internal energy on its motion as a whole and does not rely on the presence of quasiparticles in the system. The thermal equilibrium hc/2e periodicity is broken by an offset of the transition between different current-carrying states. The magnitude of the offset is calculated for an s-wave superconducting cylinder of radius R in the limit R≫ξ0, where ξ0 is the BCS coherence length and turns out to be exponentially small. A possible enhancement of the effect for nodal superconductors is suggested. Similar conclusions should also apply to the response of charged or neutral superfluids to rotation.