Wall and Bloch-line coercivity measurements in magnetic garnet films

The wall and Bloch-line motion at small magnetic fields in several garnet films has been investigated and coercive phenomena have been studied. Wall coercivity measurements have been carried out with various spatial resolutions. The coercivity curves show jumps and hysteresis effects at small observation windows. When increasing the observation window the measured curve represents the averaged response of all observed walls showing the mean value for the coercive field H c. The coercive field of vertical Bloch lines has also been measured by directly observing the Bloch lines. Both measurements, wall and Bloch line, refer to local material inhomogeneities of the garnet films.