Nonlinear Seebeck effect in Ni$_{81}$Fe$_{19}$|Pt at room temperature

Y. Hirata; T. Kikkawa; H. Arisawa; E. Saitoh

doi:10.1063/5.0269578

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arXiv · 2507.03249

Nonlinear Seebeck effect in Ni$_{81}$Fe$_{19}$|Pt at room temperature

Y. Hirata·T. Kikkawa·H. Arisawa·E. Saitoh

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Abstract

The nonlinear Seebeck effect, nonlinear conversion of a temperature gradient into an electric current, was observed at room temperature. Based on a second-harmonic lock-in method combined with an a.c. temperature gradient, $\nabla T$, we measured a nonlinear Seebeck voltage in NiFe|Pt bilayers at 300 K, the amplitude of which increases in proportion to $(\nabla T)^2$. We also observed that the nonlinear Seebeck voltage increases as the sample length along the $\nabla T$ direction decreases, showing a characteristic scaling law distinct from the conventional linear Seebeck effect. We developed a phenomenological model for the nonlinear Seebeck effect incorporating the spin-current induced modulation of the Seebeck coefficient, which well reproduces the experimental results.

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Y. Hirata, T. Kikkawa, H. Arisawa, E. Saitoh. 2025-07-04. Nonlinear Seebeck effect in Ni$_{81}$Fe$_{19}$|Pt at room temperature. https://doi.org/10.1063/5.0269578

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