Loss mechanisms in nanocrystalline magnetic ribbons

Eddy currents rise the magnetization loss with increasing frequency which is undesired in the application of soft magnetic materials. As magnetization loss is responsible for energy loss, there is great interest to study the loss mechanisms. For this purpose, a suitable technique is the magnetization loss measurement and simultaneous observation of the dynamic magnetic domain structure with time-resolved Kerr microscopy.

In Fig. 1, the magnetic power loss per cycle and domain images of nanocrystalline cores with different strengths of the induced longitudinal anisotropy K_u are shown. The domain images, that are taken around the coercive field, illustrate that a high number of active domain walls is necessary to decrease the dynamic excess loss.

Fig. 1 Specific power loss per cycle vs. frequency and corresponding domain images of nanocrystalline tape wound cores with different strength of induced longitudinal anisotropy K_u. Domain  refinement is distinctive with increasing frequency.