Thermal imaging of spin Peltier effect

TL;DR

This paper visualizes the spin Peltier effect using thermal imaging, revealing localized temperature changes at the metal/insulator interface and showing the effect is stronger than previously estimated.

Contribution

It provides the first thermal imaging of the spin Peltier effect, demonstrating localized temperature modulation and quantifying its magnitude.

Findings

Temperature change confined near the interface

Spin Peltier effect is more than ten times stronger than previously thought

Thermal images reveal characteristic heat source distribution

Abstract

When a charge current is applied to a junction comprising two different conductors, its temperature increases or decreases depending on the direction of the charge current. This phenomenon is called the Peltier effect, 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 depending on the direction of a spin current. Here we report thermal imaging of the spin Peltier effect; using active thermography technique, we visualize the temperature modulation induced by a spin current 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. The finding of this anomalous temperature distribution allows us to estimate the actual magnitude of the temperature modulation induced by the spin Peltier effect, which is found to be more than one order of magnitude greater than that previously believed.