Physics

Coupling Superconductivity and Magnetism

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Science  20 Dec 2002:
Vol. 298, Issue 5602, pp. 2287
DOI: 10.1126/science.298.5602.2287b

Superconductivity and the Kondo effect are two well-known and fairly well-understood examples of many-body systems. Both involve the interaction of electron spin, and the competition of their different coupling mechanisms has led to theoretical proposals for coupling superconductivity and magnetism. The superconductor provides a natural source of entangled electron pairs, and the repulsive interaction of localized spin in the Kondo effect spatially separates the pairs while keeping them entangled.

Buitelaar et al. connected a quantum dot to superconducting leads and show that changing the number of electrons on the dot from odd (Kondo regime) to even (non-Kondo regime) strongly affects the transport of the superconducting pairs through the dot. In particular, they show that relative strength between the Kondo correlation and the pairing strength of the superconducting pairs will be an important consideration if a source of nonlocal spin- entangled pairs is to be realized. — ISO

Phys. Rev. Lett.89, 256801 (2002).

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