Coherent transport and nonlocality in mesoscopic SNS junctions: anomalous magnetic interference patterns
✍ Scribed by Victor Barzykin; Alexandre M. Zagoskin
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 386 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0749-6036
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✦ Synopsis
We show that in ballistic mesoscopic SNS junctions the period of critical current versus magnetic flux dependence (magnetic interference pattern), I c ( ), changes continuously and nonmonotonically from 0 to 2 0 as the length-to-width ratio of the junction grows, or temperature drops. In diffusive mesoscopic junctions the change is even more drastic, with the first zero of I c ( ) appearing at 3 0 .
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 ξ T = v F /2π k B T (ballistic limit) or ξT = √ D/2π k B T (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 2 0 -periodicity recently observed by Heida et al. [Phys. Rev. B57, 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 0 → 2 0 -and 0 → 3 0 -transitions.