Thermoelectric power of palladium-iron alloys at Millikelvin temperatures

The thermoelectric powerS of a pure palladium sample and four alloys ofPdFe, containing 77–400 ppm Fe, has been measured at temperatures down to 5 mK. A sign change inS is observed at low temperatures in all of the alloys, consistent with the onset of spin-glass freezing, the crossover temperature varying as the square of Fe concentration. We also observed that these alloys could be used as useful secondary thermometers down to at least 5 mK.SRC Senior Visiting Fellow 1980, on leave from Michigan State University, Michigan.