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arXiv · 1206.2045

Observation of the Triplet Spin-Valve Effect in a Superconductor-Ferromagnet Heterostructure

V. Zdravkov·J. Kehrle·G. Obermeier·D. Lenk·H. -A. Krug von Nidda·C. Müller·A. S. Sidorenko·S. Horn·R. Tidecks·L. R. Tagirov
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Abstract

The theory of superconductor-ferromagnet (S-F) heterostructures with two ferromagnetic layers predicts the generation of a long-range, odd-in-frequency triplet pairing at non-collinear alignment (NCA) of the magnetizations of the F-layers. This triplet pairing has been detected in a Nb/Cu41Ni59/nc-Nb/Co/CoOx spin-valve type proximity effect heterostructure, in which a very thin Nb film between the F-layers serves as a normal conducting (nc) spacer. The resistance of the sample as a function of an external magnetic field shows that for not too high fields the system is superconducting at a collinear alignment of the Cu41Ni59 and Co layer magnetic moments, but switches to the normal conducting state at a NCA configuration. This indicates that the superconducting transition temperature Tc for NCA is lower than the fixed measuring temperature. The existence of a minimum Tc, at the NCA regime below that one for parallel or antiparallel alignments of the F-layer magnetic moments, is consistent with the theoretical prediction of a singlet superconductivity suppression by the long-range triplet pairing generation.

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V. Zdravkov, J. Kehrle, G. Obermeier, D. Lenk, H. -A. Krug von Nidda, C. Müller, A. S. Sidorenko, S. Horn, R. Tidecks, L. R. Tagirov. 2012-06-10. Observation of the Triplet Spin-Valve Effect in a Superconductor-Ferromagnet Heterostructure. https://doi.org/10.1103/physrevb.87.144507

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