THEORY OF ORDINARY HALL COEFFICIENT OF IRON AT LOW TEMPERATURES

The ordinary Hall coefficient R0 for body-centred cubic iron at temperatures below 100°K is analysed using a two-band model and it is shown that many of the experimental observations of Volkenshtein and Fedorov and of Dheer may be explained. These include strong dependences of R0 on temperature and on small amounts of impurity, and changes in sign of R 0. The several different scattering mechanisms of importance in pure Fe at low temperatures will each dominate in a particular region, leading to large changes in R0 in a relatively small temperature range. Parameters are introduced to describe the effects of anisotropies in the Fermi surfaces and in the relaxation times, and these are explicitly estimated for the case of scattering by impurities, using a technique whereby the wave number and the relaxation time are expanded in a series of cubic harmonics up to fourth order. The value of R0 as the temperature T -> 0°K is estimated to be (0·3 ± 0·15) × 10-13 Ω cm G-1 which is consistent with experimental data.