Temperature effects, Laves phases

The appearance of a perpendicular anisotropy in the mixed state of both amorphous and crystalline structure was reported by Miyazaki et al. (1997) for (Tbo.3Dyo.7)0.33Feo.67 films fabricated above 673 K (400°C) (see fig. 32). The thermal stability and the reproducibility of those films were studied also. For films prepared with substrate temperatures above 673 K (400°C), the magnetostriction changes remarkably after 3 months. This is due to ageing effects, related to the formation of the Laves phase (Tb,Dy)Fe2. 

The magnetic moments of rare earth elements are caused by the unpaired electrons in their 4f shells. These shells" are shielded by the outer shells so that chemical bonding has relatively little effect on the magnetic moments of these elements. The rare earths form a series of Laves phases of composition MB2 (M = rare earth, B = precious metal) which share the characteristic of ferromagnetic coupling at low temperatures (7). Figure 13 shows the Curie temperatures of a series of com-... 

---