The Hall effect has been measured on pure alpha and beta plutonium and on a 3.4 at.% aluminum-stabilized delta-phase alloy. Measurements were made between 6 and 438°K with magnetic fields up to 21 kG. In each phase, $R_o$ is positive and relatively independent of temperature at higher temperatures, but shows strong temperature dependence at low temperatures. $R_o$ for alpha plutonium becomes negative at 185°K and goes through a minimum at 23°K. The $R_o\text{'}\mathrm{s}$ for beta plutonium exhibit a maximum at 29°K and then drop sharply to negative values below 17°K. The value remains positive, with no maximum, for the delta alloy throughout the temperature range. The data were used to test a two-band model, and were found to fit best to a nearly full $7s$ band and empty $5f$ band. Because of similarities with data on the rare-earth metals, the low-temperature behavior of $R_o$ for each phase is thought to be due to antiferromagnetic ordering, but the anomalies in the electrical resistivity of the three phases are probably due to interband scattering.

• Received 9 October 1964

DOI:https://doi.org/10.1103/PhysRev.137.A1423