Longitudinal spin Seebeck effect contribution in transverse spin Seebeck effect experiments in Pt/YIG and Pt/NFO

TL;DR

This study examines the inverse spin Hall voltage in Pt on YIG and NFO, revealing that observed voltages are due to the longitudinal spin Seebeck effect caused by parasitic out-of-plane temperature gradients, challenging previous interpretations.

Contribution

It demonstrates that voltages in transverse spin Seebeck experiments can originate from the longitudinal effect due to parasitic gradients, providing new insights into experimental interpretation.

Findings

Voltages are linked to the longitudinal spin Seebeck effect.

No sign change observed when moving the Pt strip from hot to cold.

Parasitic out-of-plane temperature gradients influence measurements.

Abstract

We investigate the inverse spin Hall voltage of a 10nm thin Pt strip deposited on the magnetic insulators Y3Fe5O12 (YIG) and NiFe2O4 (NFO) with a temperature gradient in the film plane. We observe characteristics typical of the spin Seebeck effect, although we do not observe a change of sign of the voltage at the Pt strip when it is moved from hot to cold side, which is believed to be the most striking feature of the transverse spin Seebeck effect. Therefore, we relate the observed voltages to the longitudinal spin Seebeck effect generated by a parasitic out-of-plane temperature gradient, which can be simulated by contact tips of different material and heat conductivities and by tip heating. This work gives new insights into the interpretation of transverse spin Seebeck effect experiments, which are still under discussion.