Temperature Dependence of the Spin Seebeck Effect in a Mixed Valent Manganite.

We report on temperature dependent measurements of the longitudinal spin Seebeck effect (LSSE) in the mixed valent manganite La0.7Ca0.3MnO3. By disentangling the contribution arising due to the anisotropic Nernst effect, we observe that in the low temperature regime, the LSSE exhibits a T0.5 dependence, which matches well with that predicted by the magnon-driven spin current model. Across the double exchange driven paramagnetic-ferromagnetic transition, the LSSE exponent is significantly higher than the magnetization one, and also depends on the thickness of the spin-to-charge conversion layer. These observations highlight the importance of individually ascertaining the temperature evolution of different mechanisms--especially the spin mixing conductance--which contribute to the measured spin Seebeck signal. [ABSTRACT FROM AUTHOR]