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arXiv · 2509.08327

Trans-scale spin Seebeck effect in nanostructured bulk composites based on magnetic insulator

Sang J. Park·Keisuke Hirata·Hossein Sepehri-Amin·Fuyuki Ando·Takamasa Hirai·Ken-ichi Uchida
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Abstract

The spin Seebeck effect (SSE) enables thermoelectric conversion through thermally generated spin currents in magnetic materials, offering a promising transverse geometry for scalable devices. However, conventional SSE devices are confined to nanoscale thin-film architectures, with significantly restricted output power due to the intrinsic constraints of spin and magnon diffusion lengths. Here, we demonstrate a trans-scale SSE using nano-structured bulk composites composed of Pt-coated yttrium iron garnet powders fabricated via dynamic powder sputtering and low-temperature sintering. The resulting three-dimensional composites exhibit continuous Pt channels and robust mechanical integrity. Transverse thermoelectric measurements confirm isotropic SSE signals at the bulk scale. Power analysis indicates that the three-dimensional architecture enables scalable volumetric thermoelectric power generation beyond diffusion-limited thin-film SSE geometries. This work establishes a scalable platform for bulk SSE-based thermoelectrics, bridging nanoscale spin caloritronics with macroscopic device integration.

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Sang J. Park, Keisuke Hirata, Hossein Sepehri-Amin, Fuyuki Ando, Takamasa Hirai, Ken-ichi Uchida. 2025-09-10. Trans-scale spin Seebeck effect in nanostructured bulk composites based on magnetic insulator. https://doi.org/10.1038/s41467-026-75232-0

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