INFLUENCE OF THE DISLOCATION STRUCTURES ON THE BEHAVIOUR OF MAGNETIC DOMAIN WALLS IN HIGH PURITY IRON

The influence of dislocation density and arrangement on the movement of 90° magnetic domain walls (DW) was investigated by magnetomechanical damping measurements on high purity polycristalline iron. The dislocation structures created by straining at 300 K, 190 K and by straining at 77 K after prestraining at 300 K were observed by high voltage (800 KV) transmission electron microscopy (TEM). For the straining at 300 K, the effective internal stress σi and the reciprocal of the maximum magnetomechanical damping 1/QM-1 exhibit three linear stages, related to different dislocation distributions. The dislocation structures built by straining at 190 K and 77 K influence differently σi and 1/QM-1. This is linked to the more homogeneous distribution of dislocations created at low temperatures in iron