How can an external magnetic field change the magnetization direction in a soft ferrite?

In soft ferrites, as in other ferromagnetic and ferrimagnetic materials, an external magnetic field changes the direction of magnetization primarily through the reorientation of magnetic domains.12

The process occurs in three distinct stages as the field strength increases:

• Low magnetic field: The domain walls undergo reversible movements, causing domains that are already oriented in the direction of the applied field to grow at the expense of those that are unfavorably oriented.2
• Medium magnetic field: Larger, often irreversible movements of domain walls occur, significantly increasing the volume of favorably oriented domains.2
• High magnetic field: The remaining domain walls are swept out of the material, and the magnetization directions of the individual domains rotate until they are aligned parallel to the external field, reaching saturation.2

Soft ferrites are characterized by low coercive force and narrow hysteresis loops, meaning they are easily magnetized and demagnetized. This ease of response is due to the relative lack of obstacles to domain wall movement within the material's structure.132