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M. Eschrig, J. Linder, T. Yokoyama, A. Sudbo We study proximity-induced superconducting correlations in heterostructures with magnetically active interfaces. Historically, one of the hallmarks of the proximity effect in a S/N heterostructure is a minigap in the density of states in the non-superconducting part, that scales with the Thouless energy of the system and with the transmission probability of the interface. However, for spin-active interfaces, the transmission properties of spin-up and spin-down electrons are different, giving rise to spin-dependent scattering phase shifts. This leads to a rather surprizing result. Remarkably, for any interface spin polarization there is a critical interface resistance, above which the conventional singlet proximity component vanishes at the chemical potential, while an odd-frequency triplet component remains finite. At the same time, the minigap is replaced by a low-energy band with enhanced density of states. We propose a way to unambiguously observe this effect. |
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