In the past year, several groups have observed evidence for long-range spin-triplet supercurrent in Josephson junctions containing ferromagnetic (F) materials. In our work, the spin-triplet pair correlations are created by non-collinear magnetizations between a central Co/Ru/Co "synthetic antiferromagnet" (SAF) and two outer thin F layers. Here we present data showing that the spin-triplet supercurrent is enhanced up to 20 times after our samples are subject to a large in-plane magnetizing field. This surprising result can be explained if the Co/Ru/Co SAF undergoes a "spin-flop" transition, whereby the two Co layer magnetizations end up perpendicular to the magnetizations of the two thin F layers. Direct experimental evidence for the spin-flop transition comes from scanning electron microscopy with polarization analysis and from spin-polarized neutron reflectometry.
@article{arxiv.1108.5666,
title = {Optimization of spin-triplet supercurrent in ferromagnetic Josephson junctions},
author = {Carolin Klose and Trupti S. Khaire and Yixing Wang and W. P. Pratt, and Norman O. Birge and B. J. McMorran and T. P. Ginley and J. A. Borchers and B. J. Kirby and B. B. Maranville and J. Unguris},
journal= {arXiv preprint arXiv:1108.5666},
year = {2015}
}