Reciprocal Relation between Spin Peltier and Spin Seebeck Effects ^†

In recent times, the interaction between magnetization and heat currents in a magnetic material has gained a renewed interest thanks to the observation of the spin Seebeck effect (SSE) [1,2]. The SSE is the spin counterpart of the Seebeck effect that corresponds to the generation of a pure magnetization current in a magnetic insulator as consequence of a thermal gradient. This is electrically detected by means of the inverse spin Hall effect [3], that rises in a high spin orbit coupling heavy metal deposited on the magnetic insulator. Equally to the ordinary thermoelectricity, the SSE has its reciprocal effect that is the spin Peltier effect [4,5]. In this work we provide an experimental proof of the reciprocal relations between SSE and SPE [6,7] in a single bulk sample of yttrium iron garnet (YIG) covered by a platinum thin film. For both the SSE and the SPE experiments, we employ a measurement system designed for the detection of heat currents exchanged between the thermal reservoirs and the sample under test. The sample-specific value for the characteristics of both effects measured on the present YIG/Pt bilayer is (6.2 ± 0.4) × 10⁻³ KA⁻¹ at room temperature, that corresponds to the analogous for spins of the Thomson relation between thermoelectric effects.