Properties of a domain wall in a bi-stable magnetic microwire

The properties of a domain wall between axial domains in a bi-stable microwire are studied in this paper. The axial dimension of a long planar static domain wall is calculated using a simple theoretical model. The obtained value of a few millimetres is in good agreement with known experimental values. The dynamic properties of the domain wall were analysed using wall velocity versus applied field dependences v(H). Based on a simple model which includes standard damping mechanisms (eddy current damping and spin relaxation damping), the experimentally observed decrease in wall mobility in v(H) can be caused by decrease in the wall axial dimension, its length. This should be accompanied by changes in the voltage peaks induced in the pick-up coil in the Sixtus-Tonks experiment which was, however, not observed. Taking into account a stray field around the moving wall, the voltage peaks were calculated for the situation when the pick-up coil radius was much larger than the wire radius. The calculated peaks are relatively wide also for very short domain walls, and they are only slightly influenced by the wall length. This indicates that obtaining information on the wall length and changes in its length and shape from the induced voltage peaks is very difficult.