Real-time probing of magnetic domain wall dynamic

We present a study of a very seldom used way of measuring magnetic domain wall velocity, which makes it possible to have a real-time probing of the domain movement in the area illuminated by a laser spot. We have compared this method to the most usual one: although the velocities are similar, the different method do not give the same results if the laser spot is too small. It can be explained by a dendritic shape of the domain wall. By changing the size spot, we propose a basic model which describes quite well the transit time in the laser spot as a function of its size and makes it possible to extract the velocity and the depth of the dendrites.