Ferromagnetic order

Ferromagnetic ordering of two-dimensional systems with dipole-dipole and exchange interactions in the approximation of a spherical model was examined in Ref. 73. The main simplifying assumption of the spherical model is the replacement of the condition er = 1 on the orientation vectors with the weaker condition... 

Figure 3.29 Ordered arrays of magnetic dipoles, represented by arrows (a) ferromagnetic ordering, (b) antiferromagnetic ordering, and (c) ferrimagnetic ordering.

Powder diagrams of polymetalates, 19 248 [PPh4][Cd(TIPT)3], 40 446-447 (PPhJLMnCrCox),], ferromagnetic ordering, 43 229-230... 

Tamura et al, 1991) and l,3,5,7-tetramethyl-2,6-diazaadamantane-2,6-dioxyl (T = 1.48K) (Chiarelli et ai, 1993), both containing nitroxyl groups on which unpaired electrons are located. Dipole-dipole through space spin-spin interaction is the likely mechanism for ferromagnetic ordering in these materials. 

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