We identify and investigate thermal spin transport phenomena in sputter-deposited $\mathrm{Pt}/{\mathrm{NiFe}}_2{\mathrm{O}}_x$ ($4\ge x\ge 0$) bilayers. We separate the voltage generated by the spin Seebeck effect from the anomalous Nernst effect (ANE) contributions and even disentangle the 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 ${\mathrm{NiFe}}_2{\mathrm{O}}_4$ to metallic ${\mathrm{Ni}}_{33}{\mathrm{Fe}}_{67}$. A proximity-induced ANE could only be identified in the metallic $\mathrm{Pt}/{\mathrm{Ni}}_{33}{\mathrm{Fe}}_{67}$ bilayer in contrast to $\mathrm{Pt}/{\mathrm{NiFe}}_2{\mathrm{O}}_x$ ($x>0$) samples. This is verified by the investigation of static magnetic proximity effects via x-ray resonant magnetic reflectivity.

• Received 17 February 2017

DOI:https://doi.org/10.1103/PhysRevLett.119.227205