A scalable molecule-based magnetic thin film for spin-thermoelectric energy conversion

Inseon Oh,Joonki Suh,Daeseong Choe,Jungmin Park,Hyeonjung Jeong,Jung-Woo Yoo,Mi-Jin Jin,Byoung-Chul Min,Junhyeon Jo,Younghun Jo

doi:10.1038/s41467-021-21058-x

Abstract

Spin thermoelectrics, an emerging thermoelectric technology, offers energy harvesting from waste heat with potential advantages of scalability and energy conversion efficiency, thanks to orthogonal paths for heat and charge flow. However, magnetic insulators previously used for spin thermoelectrics pose challenges for scale-up due to high temperature processing and difficulty in large-area deposition. Here, we introduce a molecule-based magnetic film for spin thermoelectric applications because it entails versatile synthetic routes in addition to weak spin-lattice interaction and low thermal conductivity. Thin films of CrII[CrIII(CN)6], Prussian blue analogue, electrochemically deposited on Cr electrodes at room temperature show effective spin thermoelectricity. Moreover, the ferromagnetic resonance studies exhibit an extremely low Gilbert damping constant ~(2.4 ± 0.67) × 10−4, indicating low loss of heat-generated magnons. The demonstrated STE applications of a new class of magnet will pave the way for versatile recycling of ubiquitous waste heat.

Highlights

Spin thermoelectrics, an emerging thermoelectric technology, offers energy harvesting from waste heat with potential advantages of scalability and energy conversion efficiency, thanks to orthogonal paths for heat and charge flow
The transferred vertical spin flow will be converted into a longitudinal charge current via inverse spin Hall effect (ISHE), JLSSE ∝ Js × σ (Js and σ denote a thermally generated spin current vector and a spin polarization vector of electron, respectively)
Conventional electrodeposition at room temperature was successfully employed for the fabrication of the Cr-Prussian blue analog (PBA)-based Spin TE (STE) device

Summary

Introduction

An emerging thermoelectric technology, offers energy harvesting from waste heat with potential advantages of scalability and energy conversion efficiency, thanks to orthogonal paths for heat and charge flow. Magnetic insulators previously used for spin thermoelectrics pose challenges for scale-up due to high temperature processing and difficulty in large-area deposition. Thin films of CrII[CrIII(CN)6], Prussian blue analogue, electrochemically deposited on Cr electrodes at room temperature show effective spin thermoelectricity. Inorganic magnetic insulator films are not appropriate for practical STE applications due to scaling problem, because they are difficult to grow into a large area and in need of high temperature processing for crystallization[3,11]. PBAs are viable alternative magnetic insulators in STE devices with the advantage of versatile synthesis amenable for large area deposition at room temperature. We introduce a molecule-based magnet, Cr-PBA, as an alternative magnetic insulator for the magnon-mediated thermal-to-electrical energy conversion.

Methods

Results

Conclusion