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Can mesoscopic fluctuations reverse the supercurrent through a disordered Josephson junction?

M. Titov, Ph. Jacquod, C. W. J. Beenakker

cond-mat.mes-hallarXiv:cond-mat/0106018

Abstract

We calculate the Josephson coupling energy UJ(ϕ) (related to the supercurrent I=(2e/) dUJ/dϕ) for a disordered normal metal between two superconductors with a phase difference ϕ. We demonstrate that the symmetry of the scattering matrix of non-interacting quasiparticles in zero magnetic field implies that UJ(ϕ) has a minimum at ϕ=0. A maximum (that would lead to a π-junction or negative superfluid density) is excluded for any realization of the disorder.

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