Thermal imaging of spin Peltier effect.

Shunsuke Daimon,Eiji Saitoh,Ken-Ichi Uchida,Ryo Iguchi,Tomosato Hioki

doi:10.1038/ncomms13754

Abstract

The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. Recently, in spintronics, a spin counterpart of the Peltier effect was observed. The ‘spin Peltier effect' modulates the temperature of a magnetic junction in response to spin currents. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by spin currents injected into a magnetic insulator from an adjacent metal. The thermal images reveal characteristic distribution of spin-current-induced heat sources, resulting in the temperature change confined only in the vicinity of the metal/insulator interface. This finding allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is more than one order of magnitude greater than previously believed.

Highlights

The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics
The first observation of the spin Peltier effect (SPE) was reported by Flipse et al.[22] using a junction comprising a ferrimagnetic insulator (FI) yttrium iron garnet (YIG) and a paramagnetic metal (PM) Pt; since the SPE appears in insulators, its physics is discussed in terms of non-equilibrium magnon excitation in the same manner as the SSE5,22,23
We report the thermal imaging of the SPE in PM/FI junction systems, which makes it possible to visualize the spatial distribution of spin-current-induced temperature modulation

Summary

Introduction

The Peltier effect modulates the temperature of a junction comprising two different conductors in response to charge currents across the junction, which is used in solid-state heat pumps and temperature controllers in electronics. To observe the SPE using the LIT technique, we measured the spatial distribution of infrared radiation thermally emitted from the sample surface while applying an a.c. charge current with rectangular wave modulation (with the amplitude Jc and frequency f) to the Pt or W layer and extracted the first harmonic response of detected signals, where we set f 1⁄4 5 Hz except for f-dependent measurements (Fig. 1c and Supplementary Fig. 1).

Results

Conclusion