Size Dependent Thermopower in Mesoscopic AuFe Wires

We have combined electron heating experiments and noise thermometry to perform quantitative measurements of the thermopower in mesoscopic samples. This new measuring technique allows us to detect finite size effects in the thermopower of narrow AuFe wires with an Fe concentration ranging from 50 to 3000 ppm. The size effects emerge when reducing the width of the wires below $\simeq 300\mathrm{nm}$ and may be related to a spin-orbit induced magnetic anisotropy close to the wire surface.