paper

Manifestation of triplet superconductivity in superconductor-ferromagnet structures

arXiv:cond-mat/0303548 · doi:10.1103/PhysRevB.68.064513

Abstract

We study proximity effects in a multilayered superconductor/ferromagnet (S/F) structure with arbitrary relative directions of the magnetization . If the magnetizations of different layers are collinear the superconducting condensate function induced in the F layers has only a singlet component and a triplet one with a zero projection of the total magnetic moment of the Cooper pairs on the direction. In this case the condensate penetrates the F layers over a short length determined by the exchange energy . If the magnetizations are not collinear the triplet component has, in addition to the zero projection, the projections . The latter component is even in the momentum, odd in the Matsubara frequency and penetrates the F layers over a long distance that increases with decreasing temperature and does not depend on (spin-orbit interaction limits this length). If the thickness of the F layers is much larger than , the Josephson coupling between neighboring S layers is provided only by the triplet component, so that a new type of superconductivity arises in the transverse direction of the structure. The Josephson critical current is positive (negative) for the case of a positive (negative) chirality of the vector . We demonstrate that this type of the triplet condensate can be detected also by measuring the density of states in F/S/F structures.

arXiv comment14 pages; 9 figures. Final version, to be published in Phys. Rev. B

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