Magnetic anisotropy barrier

The structure of the Co4 molecule is shown in Fig. 10. The four Co and four oxygens from four hydroxy methyl pyridine ligands form a cubane like central C04O4 structure. The molecule has S4 symmetry. Our NRLMOL calculations confirmed the ferromagnetic ordering indicated by experiment. However, the magnetic anisotropy barrier was found to be 23 K. In the... 

Hereafter, we will assume uniaxial anisotropy, of easy-axis type, given by Eq. (3.4) (if not otherwise indicated), since it is the simplest symmetry that contains the basic elements (potential minima, barriers) responsible for the important role of magnetic anisotropy in superparamagnets. Experimental evidence for uniaxial anisotropy is given in Refs. 15 and 16. 

Fig. 29. Magnetic anisotropy energy barriers for small particles. and K,S are the barriers for shape and magnetosurface anisotropy, respectively, for metallic iron. Figure according to Boudart et al. (215).

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