1998/05/31 by Victor Barzykin, Alexandre M. Zagoskin · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mes-hall
paper · pdf · doi:10.1006/spmi.1999.0731
13 pages, 7 figures. New results on diffusive mesoscopic SNS junctions included. Typo in Eq.(27) corrected. Contribution to the special issue of Superlattices and Microstructures on mesoscopic superconductivity
arxiv created 1998/11/16 · arxiv updated 2009/11/30
We show that in \em ballistic mesoscopic SNS junctions the period of critical current vs. magnetic flux dependence (magnetic interference pattern), Ic(Φ), changes \em continuously and non-monotonically from Φ0 to 2Φ0 as the length-to-width ratio of the junction grows, or temperature drops. In \em diffusive mesoscopic junctions the change is even more drastic, with the first zero of Ic(Φ) appearing at 3Φ0. The effect is a manifestation of nonlocal relation between the supercurrent density and superfluid velocity in the normal part of the system, with the characteristic scale ξT = ℏ vF/2πkBT (ballistic limit) or ξT = √(ℏ D/2πkBT) (diffusive limit), the normal metal coherence length, and arises due to restriction of the quasiparticle phase space near the lateral boundaries of the junction. It explains the 2Φ0-periodicity recently observed by Heida et al. (Phys. Rev. B \bf 57, R5618 (1998)). We obtained explicit analytical expressions for the magnetic interference pattern for a junction with an arbitrary length-to-width ratio. Experiments are proposed to directly observe the Φ0→ 2Φ0- and Φ0→ 3Φ0-transitions.