# Quantitative disentanglement of spin Seebeck, proximity-induced and intrinsic anomalous Nernst effect in NM/FM bilayers

## TL;DR

This study quantitatively separates and analyzes the different contributions to thermally induced voltages in Pt/NiFe2O4 bilayers, distinguishing spin Seebeck, proximity-induced, and intrinsic anomalous Nernst effects, revealing their dependence on material properties.

## Contribution

It provides a detailed quantitative disentanglement of multiple thermoelectric effects in NM/FM bilayers, including the first clear identification of proximity-induced ANE in metallic Pt/NiFe2O4.

## Key findings

- Proximity-induced ANE observed only in metallic Pt/Ni33Fe67 bilayer.
- Disentanglement of spin Seebeck and anomalous Nernst effects achieved.
- Dependence of effects on conductivity and band gap of the ferromagnetic layer.

## Abstract

We identify and investigate thermal spin transport phenomena in sputter-deposited Pt/NiFe$_2$O$_{\textrm{4-x}}$ ($4\geq x \geq 0$) 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 NiFe$_2$O$_4$ to metallic Ni$_{33}$Fe$_{67}$. A proximity-induced ANE could only be identified in the metallic Pt/Ni$_{33}$Fe$_{67}$ bilayer in contrast to Pt/NiFe$_2$O$_{\rm x}$ ($x>0$) samples. This is verified by the investigation of static magnetic proximity effects via x-ray resonant magnetic reflectivity.