EVIDENCE FOR THE INTERACTION BETWEEN 90-DEGREES DOMAIN-WALLS AND DISLOCATION TANGLES IN HIGH-PURITY IRON FROM MAGNETOMECHANICAL DAMPING EXPERIMENTS

The internal stress field, σi, which mobile 90° magnetic domain walls have to overcome can be determined by magnetomechanical damping experiments. It is shown on iron specimens strained up to 3% at room temperature, that σi is proportional to the square root of the dislocation density i.e. to the density of tangled dislocations. During further straining at 77 K, it is observed that the mobility of the 90° domain walls increases while the dislocation density inside the tangles decreases. A satisfactory interpretation of the low temperature results is obtained by calculating the dependance of σi on the density of tangled dislocations for a specimen prestrained 3% at room temperature.