Exchange coupling between two magnetic layers through an interlayer is of broad interest for numerous recent applications of nano-magnetic systems. In this Letter we study ferromagnetic exchange coupling through amorphous paramagnetic Fe-Ta alloys. We show that the exchange coupling depends exponentially on spacer thickness and scales with the Fe-Ta susceptibility, which can be tuned via the alloy composition and/or temperature. Such materials are of high interest for the engineering of perpendicularly magnetized CoFeB-MgO based tunnel junctions as it enables ferromagnetic coupling of magnetic layers with differing crystalline lattices, suppresses dead layers and can act as an inter-diffusion barrier during annealing.
@article{arxiv.1304.2763,
title = {Paramagnetic Fe_xTa_{1-x} alloys for engineering of perpendicularly magnetized tunnel junctions},
author = {Matthias Gottwald and Jimmy J. Kan and Kangho Lee and Seung H. Kang and Eric E. Fullerton},
journal= {arXiv preprint arXiv:1304.2763},
year = {2013}
}