We report on the determination of the anomalous spin Hall angle in the ferromagnetic metal alloy cobalt-iron (Co25Fe75, CoFe). This is accomplished by measuring the spin injection/detection efficiency in a multiterminal device with nanowires of platinum (Pt) and CoFe deposited onto the magnetic insulator yttrium iron garnet (Y3Fe5O12, YIG). Applying a spin-resistor model to our multiterminal spin transport data, we determine the magnon conductivity in YIG, the spin conductance at the YIG/CoFe interface and finally the anomalous spin Hall angle of CoFe as a function of its spin diffusion length in a single device. Our experiments clearly reveal a negative anomalous spin Hall angle of the ferromagnetic metal CoFe, but a vanishing ordinary spin Hall angle. This is in contrast to the results reported for the ferromagnetic metals Co and permalloy.
@article{arxiv.1905.00663,
title = {Anomalous spin Hall angle of a metallic ferromagnet determined by a multiterminal spin injection/detection device},
author = {Tobias Wimmer and Birte Coester and Stephan Geprägs and Rudolf Gross and Sebastian T. B. Goennenwein and Hans Huebl and Matthias Althammer},
journal= {arXiv preprint arXiv:1905.00663},
year = {2020}
}