Spin Seebeck coefficients of Fe, Co, Ni, and Ni80Fe20 3d-metallic thin films

It is challenge to quantitatively determine the spin Seebeck effect (SSE) of ferromagnetic metals (FM) due to many other thermoelectric signals including the anomalous Nernst effect (ANE), magnetic proximity-induced ANE, and inverse spin Hall effect (ISHE) in FM. By comparing the thermoelectric signals of single FM layer and FM/Pt bilayer and model-assisted analyses of ISHE contribution in FM, we are able to determine the pure SSE signals and the spin Seebeck coefficients of Fe, Co, Ni, and Ni80Fe20 over a temperature range from 90 to 300 K. The spin-dependent Seebeck coefficients S-up arrow and S-down arrow, which is related to the density of states of FM, were also determined experimentally by combining the conventional Seebeck coefficient and the SSE coefficient. We further suggest the calculation of the SSE coefficient should include the spin-dependent conductivities via S-s sigma S-up arrow(up arrow)- sigma S-down arrow(down arrow)/ sigma(up arrow)+ sigma(down arrow).

Automated summary

The challenge in quantitatively determining the spin Seebeck effect in ferromagnetic metals lies in the presence of various other thermoelectric signals, including the anomalous Nernst effect, magnetic proximity-induced ANE, and inverse spin Hall effect. By comparing different material layers and conducting model-assisted analyses, the pure spin Seebeck signals and coefficients of various ferromagnetic metals can be accurately determined. Understanding the properties of spin-related effects in ferromagnetic metals is crucial, and experimental measurements combined with theoretical calculations offer valuable insights into these phenomena.