Abstract
Amorphous ribbons have a large core loss at high-frequency driving field because of their wide magnetic domains. In this paper, we report on the improvement for high frequency loss by scratching or local crystallization.
The core loss measured at 20 kHz decreases by scratching or local crystallization, and this effect becomes remarkable with decreasing the space of scratches or locally crystallized regions. On the contrary, the squareness ratio of the DC hysteresis loops becomes small and then the DC hysteresis loss increases after scratching or local crystallization.
It is observed that magnetic domains are refined by scratching. However, this refinement occurs only in the vicinity of scratches when the space of scratches is wide. When the spaces are narrow, domains are refined in all the region between scratches and the number of domain walls is lagre. In the case of local crystallization, it is also observed that domains are refined.
These results suggest that the observed improvement in high frequency core loss can be attributed to the decrease in the eddy current loss which is caused by the refinement of magnetic domains.
