Ferromagnetic, domain rotation

Thus, their motion is the result of the rotation of ferromagnetic domains. 

Figure 7. Illustration of partial domain wall formation in an AF layer when the AF is sandwiched between two FM layers. (A) When the AF thickness (tAF) is very small compared to So, no partial DW is formed and the two FM are direct coupled and the AF follows the rotation of the ferromagnets. (B) When tAF is sufficiently large, a partial DW forms with a critical angle starting from 90° up to which the AF moments can be twisted and (C) when tjp > So, a 180° DW is established.

A single domain ferromagnetic particle suspended in a fluid is subject to two orientational variational mechanisms. The first is that discussed already and takes place inside the particle, it is the solid state mechanism known as Neel [25] relaxation. The second is due to the rotation of the... 

Figure 15.7 Relationship between domains and hysteresis, a) Typical hysteresis loop for a ferromagnet. h) For a virgin sample, // = 0 and M = 0 due to closure domains, (c) With increasing H, the shaded domain which was favorably oriented to H grows by the irreversible movement of domain walls up to point X. (d) Beyond point X, magnetization occurs only by the rotation of the moments, (e) Upon removal of the field, the irreversibility of the domain wall movement results in a remnant magnetization i.e., the solid is now a pennanent magnet.

---