Heterostructures composed of ferromagnetic layers that are mutually interacting through a nonmagnetic spacer are at the core of magnetic sensor and memory devices. In the present study, layer-resolved ferromagnetic resonance was used to investigate the coupling between the magnetic layers of a Co/MgO/Permalloy magnetic tunnel junction. Two magnetic resonance peaks were observed for both magnetic layers, as probed at the Co and Ni L3 x-ray absorption edges, showing a strong interlayer interaction through the insulating MgO barrier. A theoretical model based on the Landau-Lifshitz-Gilbert-Slonczewski equation was developed, including exchange coupling and spin pumping between the magnetic layers. Fits to the experimental data were carried out, both with and without a spin pumping term, and the goodness of the fit was compared using a likelihood ratio test. This rigorous statistical approach provides an unambiguous proof of the existence of interlayer coupling mediated by spin pumping.
@article{arxiv.2101.08157,
title = {Spin-current mediated exchange coupling in MgO-based magnetic tunnel junctions},
author = {L. Gladczuk and L. Gladczuk and P. Dluzewski and K. Lasek and P. Aleshkevych and D. M. Burn and G. van der Laan and T. Hesjedal},
journal= {arXiv preprint arXiv:2101.08157},
year = {2021}
}