Investigation of the effect of neighboring materials on the Anomalous Nernst effect

Abstract

The Anomalous Nernst effect (ANE) is an important mechanism that enables magnetic metals to be used for heat-to-electrical energy conversion. This phenomenon has been thought to be independent of neighboring layers. Contrary to this assumption, this paper shows theoretical and experimental evidence of how the neighboring layer affects the ANE voltage signal. First, we investigated the voltage generated in a Py/Cu bilayer, with Ta, Pt, and SiO2 as capping layer materials. Next, we performed a Py thickness dependence study of the thermal voltage in the same sample sets. Both simulated and experimental results suggest that the spin current calculated/measured within the ferromagnetic materials can be altered by the boundary conditions, and the effect of the neighboring materials is more significant for thin Py. Second, we compared the thermal voltages generated from the sample 3Py/6Cu/3Py/4SiO2 and 3Py/6Pt/3Py/4SiO2. Then, the thermal voltage generated from the same sample set was examined after insertion of a silicon dioxide layer, as in 3Py/3Cu/2SiO2/3Cu/3Py/4SiO2 and 3Py/3Pt/2SiO2/3Pt/3Py/4SiO2. We found that the insertion of the SiO2 layer between two Cu layers lowers the size of the thermal voltage remarkably comparing to when the SiO2 layer is inserted between two Pt layers.