Detection of DC currents and resistance measurements in longitudinal spin Seebeck effect experiments on Pt/YIG and Pt/NFO

TL;DR

This study explores DC current detection and resistance measurements in LSSE experiments on Pt/YIG and Pt/NFO, revealing how test currents influence the LSSE signal and Pt resistance.

Contribution

It introduces direct DC current detection as an alternative to voltage measurements and examines the impact of test currents on resistance in LSSE setups.

Findings

DC currents in the nA range can be detected in LSSE experiments.

Test currents affect the shape of the LSSE response.

Pt layer resistance varies with test current.

Abstract

In this work we investigated thin films of the ferrimagnetic insulators YIG and NFO capped with thin Pt layers in terms of the longitudinal spin Seebeck effect (LSSE). The electric response detected in the Pt layer under an out-of-plane temperature gradient can be interpreted as a pure spin current converted into a charge current via the inverse spin Hall effect. Typically, the transverse voltage is the quantity investigated in LSSE measurements (in the range of \mu V). Here, we present the directly detected DC current (in the range of nA) as an alternative quantity. Furthermore, we investigate the resistance of the Pt layer in the LSSE configuration. We found an influence of the test current on the resistance. The typical shape of the LSSE curve varies for increasing test currents.