Cooper pair splitting in ballistic ferromagnetic SQUIDs

P. L. Stroganov and Ya. V. Fominov
Phys. Rev. B 96, 174508 – Published 15 November 2017

Abstract

We consider ballistic SQUIDs with spin filtering inside half-metallic ferromagnetic arms. A singlet Cooper pair cannot pass through an arm in this case, so the Josephson current is entirely due to the Cooper pair splitting, with two electrons going to different interferometer arms. In order to elucidate the mechanisms of Josephson transport due to split Cooper pairs, we assume the arms to be single-channel wires in the short-junction limit. Different geometries of the system (determined by the length of the arms and the phases acquired by quasiparticles during splitting between the arms) lead to qualitatively different behavior of the SQUID characteristics (the Andreev levels, the current-phase relation, and the critical Josephson current) as a function of two control parameters, the external magnetic flux and misorientation of the two spin filters. The current-phase relation can change its amplitude and shape, in particular, turning to a π junction form or acquiring additional zero crossings. The critical current can become a nonmonotonic function of the misorientation of the spin filters and the magnetic flux (on half of period). Periodicity with respect to the magnetic flux is doubled, in comparison to conventional SQUIDs.

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  • Received 15 August 2017
  • Revised 31 October 2017

DOI:https://doi.org/10.1103/PhysRevB.96.174508

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

P. L. Stroganov1 and Ya. V. Fominov2,3

  • 1Moscow Institute of Physics and Technology, 141700 Dolgoprudny, Russia
  • 2L. D. Landau Institute for Theoretical Physics RAS, 142432 Chernogolovka, Russia
  • 3National Research University Higher School of Economics, 101000 Moscow, Russia

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Issue

Vol. 96, Iss. 17 — 1 November 2017

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