Hall Effect in Li, Na, and K in the Range 6-300°K

The temperature dependence of the Hall coefficients RH of the alkali metals lithium, sodium, and potassium have been determined in the approximate temperature range 6-300^∘{}K in a magnetic field of 15 kG. Values of the effective number of electrons per atom n* are deduced. At room temperature, n* for each of the metals is very close to unity, but falls slightly below this value as the temperature is reduced. It is shown that such behavior is consistent with the anisotropic phonon spectrum of these metals. The n*-versus-temperature curve shows a minimum at about D5, and qualitative explanations of this effect are attempted on the basis of scattering by residual impurities or a phonon-drag contribution to RH. Similar measurements have been made on dilute K-Na and K-Rb alloys, which indicate the possibility of anisotropic impurity scattering in potassium.