Anisotropy dysprosium

Figure 6.8 (a) Direction of local anisotropy axes (dashed lines) and the low-temperature alignment of magnetic moments (blue arrows) on dysprosium ions along the chain in crystal [(CuUjDyKMotCNlg] ... 

The above examples are SMMs of the 3d f series. In some of the 3d f SMMs, the major anisotropy comes from the 3d ions, such as Mn +, Co + or Fe + [111, 112]. There are some pure 4f clusters that behave as SMMs [115,116]. Powell and coworkers reported two pure lanthanide SMMs in 2006 [116], both of which are dysprosium clusters and they share a similar... 

Dysprosium. Large axial anisotropy confines the moments on Dy to the basal plane. Between Jn = 178 K and 7c = 85K, a helical AFM spin structure is present. The helix angle decreases with lower temperature. At 7c, an orthorhombic distortion of the hep lattice occurs and the transition into the FM state is of first order. The spins all have the same magnitude and all point along the orthorhombic a axis, so this is a simple FM structure. 

In early studies, Sagawa et al. (1984a,b) already pointed out the effects of additives such as Co and Dy on improvements of the magnetic properties, especially the Curie temperature (Tc) and coercivity (Hcj), respectively, of Nd-Fe-B sintered magnets. Dy addition increases the intrinsic anisotropy field, which results in an increase of coercivity. The disadvantage of Dy addition, however, is the high cost of dysprosium. 

Fig. 6.27. The results of Feron et al. (1970) for the uniaxial anisotropy coefficient kJ of dysprosium and terbium plotted as a function of the reduced magnetization.

Fig. 6.29. The basal plane anisotropy of dysprosium as a function of reduced magnetization. The results of Martin s, re-analysis of Rhyne s (1%5) magnetostriction measurements are shown. (Me.rhn and Rhynt, imj.

Fig. 14.128. The variation of the ordering temperature and critical field with composition of Dy-Co compounds. The magnetization at 160 kOe is given as a rough indication of anisotropy effects. Elemental dysprosium is shown in the form of filled squares with the ordering tempera ture normalized to the Tc curve (Taylor and Primavesi, 1972a).

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