We study the flow of a pure spin current through zinc oxide by measuring the spin Hall magnetoresistance (SMR) in thin film trilayer samples consisting of bismuth-substituted yttrium iron garnet (Bi:YIG), gallium-doped zinc oxide (Ga:ZnO), and platinum. We investigate the dependence of the SMR magnitude on the thickness of the Ga:ZnO interlayer and compare to a Bi:YIG/Pt bilayer. We find that the SMR magnitude is reduced by almost one order of magnitude upon inserting a Ga:ZnO interlayer, and continuously decreases with increasing interlayer thickness. Nevertheless, the SMR stays finite even for a 12nm thick Ga:ZnO interlayer. These results show that a pure spin current indeed can propagate through a several nm-thick degenerately doped zinc oxide layer. We also observe differences in both the temperature and the field dependence of the SMR when comparing tri- and bilayers. Finally, we compare our data to predictions of a model based on spin diffusion. This shows that interface resistances play a crucial role for the SMR magnitude in these trilayer structures.
@article{arxiv.1612.07239,
title = {Pure spin current transport in gallium doped zinc oxide},
author = {Matthias Althammer and Joynarayan Mukherjee and Stephan Geprägs and Sebastian T. B. Goennenwein and Matthias Opel and M. S. Ramachandra Rao and Rudolf Gross},
journal= {arXiv preprint arXiv:1612.07239},
year = {2017}
}