Observation of spin Seebeck contribution to the transverse thermopower in Ni-Pt and MnBi-Au bulk nanocomposites

Abstract

Transverse thermoelectric devices produce electric fields perpendicular to an incident heat flux. Classically, this process is driven by the Nernst effect in bulk solids, wherein a magnetic field generates a Lorentz force on thermally excited electrons. The spin Seebeck effect (SSE) also produces magnetization-dependent transverse electric fields. SSE is traditionally observed in thin metallic films deposited on electrically insulating ferromagnets, but the films' high resistance limits thermoelectric conversion efficiency. Combining Nernst and SSE in bulk materials would enable devices with simultaneously large transverse thermopower and low electrical resistance. Here we demonstrate experimentally this is possible in composites of conducting ferromagnets (Ni or MnBi) containing metallic nanoparticles with strong spin-orbit interactions (Pt or Au). These materials display positive shifts in transverse thermopower attributable to inverse spin Hall electric fields in the nanoparticles. This more than doubles the power output of the Ni-Pt materials, establishing proof-of-principle that SSE persists in bulk nanocomposites.

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Cited by in corpus (10)

• Thermoelectrics: from Longitudinal to Transverse
• Giant Enhancement of Intrinsic Spin Hall Conductivity in $\beta$ Tungsten via Substitutional Doping
• Observation of anomalous Ettingshausen effect and large transverse thermoelectric conductivity in permanent magnets
• Magnon and Phonon Dispersion, Lifetime and Thermal Conductivity of Iron from Spin-Lattice Dynamics Simulations
• Interface-induced anomalous Nernst effect in Fe3O4/Pt-based heterostructures
• Fundamentals and advances in transverse thermoelectrics
• Permanent-magnet-based transverse thermoelectric generator with high fill factor driven by anomalous Nernst effect
• Seebeck-driven transverse thermoelectric generation in magnetic hybrid bulk materials
• Spin Seebeck effect in a simple ferromagnet near Tc: A Ginzburg-Landau approach
• Spin caloritronics: History and future prospects of experiments