Thermoelectric Signal Enhancement by Reconciling the Spin Seebeck and Anomalous Nernst Effects in Ferromagnet/Non-magnet Multilayers

TLDR

Ferromagnetic materials in thermoelectric devices enable simpler structures and independent tuning of electrical and thermal conductivities, potentially overcoming current technological barriers. The study investigates thermoelectricity in FM/NM multilayers under optical heating, systematically varying the NM material and the number of layers. By selecting NM materials whose spin Hall angle matches the sign of the anomalous Nernst effect and increasing the multilayer count, the thermoelectric voltage is amplified while resistance drops, demonstrating a viable route toward magnetic‑based thermoelectric devices.

Abstract

Abstract The utilization of ferromagnetic (FM) materials in thermoelectric devices allows one to have a simpler structure and/or independent control of electric and thermal conductivities, which may further remove obstacles for this technology to be realized. The thermoelectricity in FM/non-magnet (NM) heterostructures using an optical heating source is studied as a function of NM materials and a number of multilayers. It is observed that the overall thermoelectric signal in those structures which is contributed by spin Seebeck effect and anomalous Nernst effect (ANE) is enhanced by a proper selection of NM materials with a spin Hall angle that matches to the sign of the ANE. Moreover, by an increase of the number of multilayer, the thermoelectric voltage is enlarged further and the device resistance is reduced, simultaneously. The experimental observation of the improvement of thermoelectric properties may pave the way for the realization of magnetic-(or spin-) based thermoelectric devices.