Quantitative Disentanglement of the Spin Seebeck, Proximity-Induced, and Ferromagnetic-Induced Anomalous Nernst Effect in Normal-Metal-Ferromagnet Bilayers
We identify and investigate thermal spin transport phenomena in
sputter-deposited Pt/NiFe2O4-x (4≥x≥0) bilayers. We
separate the voltage generated by the spin Seebeck effect from the anomalous
Nernst effect contributions and even disentangle the intrinsic anomalous Nernst
effect (ANE) in the ferromagnet (FM) from the ANE produced by the Pt that is
spin polarized due to its proximity to the FM. Further, we probe the dependence
of these effects on the electrical conductivity and the band gap energy of the
FM film varying from nearly insulating NiFe2O4 to metallic
Ni33Fe67. A proximity-induced ANE could only be identified in the
metallic Pt/Ni33Fe67 bilayer in contrast to Pt/NiFe2Ox
(x>0) samples. This is verified by the investigation of static magnetic
proximity effects via x-ray resonant magnetic reflectivity