Anomalous Nernst Effect in Co_xPd_1-x alloy films

The anomalous Nernst effect (ANE) in Co_xPd_1-x alloy thin films has been investigated for the first time over a range of cobalt concentrations (x = 0.19 - 0.55) in samples prepared by electrodeposition. The films were characterized from both the magnetic and thermoelectric point of view, by means of alternating gradient force magnetometry and studying the Nernst and Seebeck effects, in order to assess their suitability for transverse thermoelectric energy conversion. In the adopted experimental setup, maximization of the ANE signal requires a preferential magnetization direction perpendicular to the film plane. It is known that, for this alloy, at co concentrations x <~ 0.4 the perpendicular magnetic anisotropy overcomes the shape anisotropy; such behavior was verified in the present work through magnetization curves, and correlated with the variations observed in the Nernst signal. The anomalous Nernst coefficient S_ANE was found to increase with co concentration, reaching a maximum value of 0.43 µV*(K)^-1 for the highest measured cobalt content. The obtained values are comparable with those reported for analogous alloys such as Co_xPt_1-x. We have also measured the transverse thermoelectric voltage at zero applied magnetic field s_0, since this would eventually be the figure of interest in practical energy harvesting applications. We have obtained a maximum value of s_0 = 0.11 µV*(K)^-1 at x = 0.37, highlighting the fact that the coefficient s_0 is affected not only by the intrinsic ANE value, but also by extrinsic factors.