Effect of Dislocations on the Initial Susceptibility of Nickel Single Crystals

The magneto-elastic interaction between dislocations and a 180° domain wall in a ferromagnetic material has already been investigated and the initial susceptibility has been expressed as a function of dislocation density. In this study, the initial susceptibility was measured at room temperature for nickel single crystals plastically deformed in tension. The dislocation density estimated from these experiments is found to be in quantitative agreement with other experimental and theoretical results for the stage I of the shear stress-strain curve. In the stage II, however, it does not agree with them, unless the change of the magnetic domain structure in a heavily deformed state is taken into consideration. Further, at 90° and 150℃ where the magnetic anisotropy of nickel approaches zero, the influence of the shear stress on the initial susceptibility χ_0 was studied. As the results of these experiments, it becomes evident that the inverse initial susceptibility χ_0^ varies linearly with the shear stress in both stages I and II, and its slope in the stage I is about 50% larger than that in the stage II