The electrical resistance of aluminium at low temperatures

Abstract

The electrical resistance of aluminium at low temperatures has been the subject of numerous investigations. The general results of the studies made previous to 1926 have been summarized by Tuyn and Kamerlingh Onnes. Subsequent researches have been mainly concerned with measurements at liquid helium temperatures. These have been made by Tuyn and Kamerlingh Onnes, by Meissner and Viogt, and by Keesom, who discovered that aluminium becomes superconducting at about 1·14° K. The data given by Meissner and Voigt for Al, as well as for several other metals ( e. g ., Mo, Co, and Mg), appear to show that the resistance in the range 4·2° K to 1·3° K is not constant, but increases slightly with decreasing temperature. The measurements of Tuyn and Kamerlingh Onnes and of Keesom show no such phenomenon, the resistance of their aluminium specimens remaining constant, within the experimental error, between these temperatures. However, the resistance ratio R 4·2° K /R 0°C for the specimen used by Tuyn and Kamerlingh Onnes was 0·067 and for the specimens of Keesom 0·073 and 0·039, while the four specimens used by Meissner and Voigt show considerably smaller values, viz., 0·0197, 0·0148, 0·0079, and 0·0065, suggesting that their aluminium was of higher purity than that used by Tuyn and Kamerlingh Onnes and by Keesom.