Spin Seebeck insulator

TL;DR

This paper demonstrates that magnetic insulators can generate electric voltage from heat flow via the spin Seebeck effect, expanding thermoelectric material options beyond conductors.

Contribution

It reveals heat-to-electricity conversion in insulators through spin voltage, involving interface spin exchange and inverse spin Hall effect, a novel mechanism in thermoelectric research.

Findings

Electric voltage generated in insulators without conduction electrons.

Spin Seebeck effect observed in LaY2Fe5O12 with Pt films.

Extension of thermoelectric materials to magnetic insulators.

Abstract

Thermoelectric generation is an essential function of future energy-saving technologies. However, this generation has been an exclusive feature of electric conductors, a situation which inflicts a heavy toll on its application; a conduction electron often becomes a nuisance in thermal design of devices. Here we report electric-voltage generation from heat flowing in an insulator. We reveal that, despite the absence of conduction electrons, a magnetic insulator LaY2Fe5O12 converts a heat flow into spin voltage. Attached Pt films transform this spin voltage into electric voltage by the inverse spin Hall effect. The experimental results require us to introduce thermally activated interface spin exchange between LaY2Fe5O12 and Pt. Our findings extend the range of potential materials for thermoelectric applications and provide a crucial piece of information for understanding the physics of the spin Seebeck effect.