Anomalous reversal of transverse thermoelectric voltage in CoδFe100-δ/YIG junction

We have studied thermoelectric conversion in all-ferromagnetic CoδFe100-δ/YIG bilayer junctions as a function of the chemical composition δ. We performed measurements of the transverse thermoelectric voltage upon application of a magnetic field. The voltage measured in the longitudinal spin Seebeck effect configuration shows a sign reversal at δ = 40%, which cannot be explained by the conventional electronic transport, such as the anomalous Nernst and Hall effects in the CoδFe100-δ layer. Our results suggest a possible role of the sd-type exchange interaction between Co40Fe60 and YIG at the interface as a possible origin for the observed behavior.