Temperature dependence of the domain wall magneto-Seebeck effect: avoiding artifacts of lead contributions

Abstract

We study the resistive and thermopower signatures of a single domain wall in a magnetic nanowire in the temperature range from 4 K to 204 K. The results are compared to the anisotropic magnetoresistance (AMR) and anisotropic magneto-Seebeck (AMS) data of the whole permalloy nanowire. The AMS ratio of the nanowire reveals a sign change at a temperature of 98 K, while the AMR ratio is positive over the complete temperature range. This behavior is also observed for the domain wall, allowing an attribution of the measured signatures to the domain wall magneto-Seebeck and domain wall magnetoresistive contributions. However, the observed zero crossing of the AMS ratio, in both types of measurements is not expected for permalloy, since the Mott formula predicts a temperature dependency of the AMS identical to the AMR. We discuss the origin of this behavior and can attribute it to the contributions of the lead and the protective platinum layer used in our devices. A correction scheme is presented and applied. Such contributions could also play a role in the analysis of magneto-Seebeck effects in other nanoscale devices, such as the tunnel magneto-Seebeck effect of magnetic tunnel junctions.