The influence of plastic deformation on the transverse magnetoresistance of polycrystalline copper, silver and gold

The transverse magnetoresistance of annealed and of plastically deformed wires of copper, silver and gold was measured at 20°K and 14°K. When the results are plotted in a Kohler diagram, the deformed material yields a curve which is in general shifted with respect to the curve for the annealed metal. This shift is shown to be temperature dependent; both positive and negative shifts have been found. In many cases recovery at temperatures below 150–200°C only has a small influence on the position of the curve; it returns to its original position, however, upon annealing at sufficiently high temperatures. We therefore assume that the shift is caused by the dislocations present in the deformed metal. In silver the recovery stage at −120°C causes an additional shift, which seems to be independent of the temperature in the region investigated; this effect also disappears upon annealing. Probably the shift can be explained by considering the anisotropic scattering of the conduction electrons by dislocations; a satisfactory theory, in particular concerning the temperature dependence, has not yet been found, however.