Nernst measurements in thin Pt and W wires at low temperatures

With the rapid growth of interest in spin caloritronics studies of magnetic insulators, including at cryogenic temperatures, it is important to understand potential confounding effects that arise in strong spin-orbit metals. We provide detailed measurements of the Nernst response of Pt and W wires at low temperatures utilizing an experimental configuration familiar from local spin Seebeck measurements. For thin wires of Pt on oxidized Si substrates, we find that the Nernst response at fixed power decreases with increasing temperature. We use finite element thermal modeling and Johnson-Nyquist noise measurements of the wires to evaluate the thermal environment during the Nernst measurements. We compare the measured results with theoretical expectations for these systems.