Hall effect at low temperatures for rare earth metals
Measurements of the Hall effect in metallic lanthanum, cerium, praseodymium, and neodymium were carried out in the temperature range from 20.3°K. to 300°K. For gadolinium, dysprosium, and erbium, the measurements were made quantitatively only above the respective Curie temperatures, the range of temperatures for gadolinium being from 30°C to 350°C. Insofar as possible, magnetic effects were taken account of and values obtained for the ordinary Hall coefficients. The results for each metal are summarised below. (1) Lanthanum showed an unknown crystal structure and the magnitude of the Hall coefficient was strongly dependent on heat treatment. As received, the Hall coefficient at room temperature was -0.35 x 10 -12 volt-cm/amp-oersted, after annealing it was about -0.8 x 10-12 volt-cm/amp-oersted, and was changed by further annealing. The Hall effect showed some rather large variations in magnitude with temperature but remained negative in sign at all temperatures studied. (2) Cerium exhibited nothing but face-centered cubic structure at room temperature after either annealing or cycling to low temperatures. The room temperature value of the Hall coefficient after annealing was +1.81 x 10-12 volt-cm/amp-oersted and this was reproducible for various samples to better than 1 percent. The value at room temperature after the first and subsequent cycles to low temperatures was +1.41 x 10-12 volt-cm/amp-oersted. Reannealing raised this back up to the higher value.