Inkjet‐Printed Flexible Spin Seebeck Thermopile Device for Low‐Cost Spintronics Device Fabrication

Abstract

Spin‐momentum‐mediated heat–charge conversion technologies for developing thin thermoelectric generators and heat flow sensors have been extensively studied. The thermoelectric generation (TEG) based on the spin Seebeck (SSE) effect is a promising technology. In this study, a flexible SSE thermopile device is fabricated using inkjet printing with Fe3O4 and Ag nanoparticle (NP) ink. A square Fe3O4 NP and a wire‐shaped Ag NP layer are used as the first and second layers, respectively. These layers are overlaid using inkjet printing twice. To obtain the SSE voltage (VSSE), a thin Pt film is deposited on a printed thermopile device. SSE generators consisting of a Pt thin film/Fe3O4 NP layer are connected through a Ag NP wire to form a thermopile structure. The saturated VSSE of the SSE thermopile device increases with the number of SSE generators. In addition, the SSE‐TEG of an SSE thermopile device is observed using a heat source with a curved surface. In these results, it is indicated that the inkjet‐printing fabrication method holds great potential in both the SSE thermopile devices and the flexible spintronic devices because it is a simple and fast process that does not require lithography.