Abstract
Measurements have been made of the temperature dependence of the Hall effect in the range 1-300°K, and of the transverse and longitudinal magnetoresistance at low temperatures, in [100] and [111] iron whiskers of high purity (resistance ratios extrapolated to ranged from 242 to 852). Analysis of the Hall data shows that both the "ordinary" Hall coefficient and the "extraordinary" Hall coefficient vary enormously with temperature, and these variations cannot be explained by existing theories. The theoretical relation , where is the resistivity, does not hold for temperatures below that of liquid nitrogen, and around this temperature , which is positive at room temperature (hole conduction), becomes negative. and appear to be isotropic, but at low temperatures these coefficients are extremely sensitive to impurities. The longitudinal magnetoresistance at 4.2°K shows a large effect of the domain structure on the electrical resistance, which decreases appreciably (46% for the purest specimen) on magnetizing the specimens to saturation. Small negative magnetoresistance (∼10%) has also been observed for some specimens in weak transverse fields.
- Received 25 July 1966
DOI:https://doi.org/10.1103/PhysRev.156.637
©1967 American Physical Society