Electrical Resistivity of Alkali Metals Below 20° K

Abstract

THE change of the electrical resistivity of pure metals at temperatures below 20° K. is of considerable theoretical importance. While there is available a great body of experimental data at the temperatures of liquid hydrogen and helium, only one set of experiments¹ exists in the intervening region, which covers a 5 : 1 ratio in absolute temperature. Since for most metals the resistance becomes largely independent of temperature below 4° K., this region (between 4° and 20° K.) is crucial for determining the law of resistance variation with temperature. We have now modified a previously described helium cryostat² working on the Simon expansion principle for continuous work between 1·5° and 20° K., temperatures being determined by a gas thermometer, and the electrical resistance with a sensitive galvanometer amplifier³.