Solid ferrimagnetic

H. Alfven (Stockholm) discoveries in magneto-hydrodynamics with fruitful applications in different parts of plasma physics. L. Neel (Grenoble) discoveries concerning antiferromagnetism and ferrimagnetism which have led to important applications in solid state physics. 

Figure S6.1 Magnetic structures (a) paramagnetic solid, (b) ferromagnetic ordering, (c) antiferromagnetic ordering, and (d) ferrimagnetic ordering. The magnetic dipoles on atoms are represented by arrows.

Hence, the ferromagnetic or ferrimagnetic behavior of a material is not a property of a molecule or an ion. Like electric conductivity, it is a cooperative property seen only in the solid state, in assembles of molecules. 

Magnetorheological materials (fluids) are the magnetic equivalent of electrorheological fluids. In this case, the particles are either ferromagnetic or ferrimagnetic solids that are either dispersed or suspended within a liquid and the applied field is magnetic (14). 

Birss, R.R., Martin, D.J. (1975) The magnetization process in hexagonal ferromagnetic and ferrimagnetic single crystals, J.Phys.C Solid State Phys. 8 189-210. 

Ferrimagnetic solids have a net magnetization that tends to cancel individual moments, and they have considerable resistance to reorientation of these moments however, the individual moments are usually of two kinds, one large, one small, so that the antiparallel ordering of moments yields some net overall magnetization. 

Figure 8. Schematic illustration of spin-glass cluster formation in ilmenite-rich members of the ilmenite-hematite solid solution (after Ishikawa et al. 1985). Dashed lines show ferrimagnetic clusters surrounding Fe cations within the (001) Ti layers. Atoms labelled F have fmstrated spins.

Figure 13. Model of self-reversal in the ilmenite-hematite solid solution (after Hoffman 1992). Boxes represent (001) cation layers (viewed down the c-axis), shaded according to their Fe-occupancy (Fe = dark, Ti = light). Two ordered ferrimagnetic domains are shown (left and right) separated by a twin wall (central) with a canted antiferromagnetic stmeture. (a) The twin wall orders first with its parasitic moment parallel to the external field. The ferrimagnetic domains order perpendicular to external field and antiparallel to each other, (b) The domain moments tilt away from the wall moment at lower temperatnres, creating a large reverse component of magnetization.

Riste T, Tenzer L (1961) A neutron diffraction study of the temperature variation of the spontaneous sublattice magnetization of ferrites and the Neel theory of ferrimagnetism. J Phys Chem Solids 19 117-123... 

Miller et al. have also synthesised two rare earth analogues based on TCNE and Gd and Dy. The former is a spin-only ion and the latter has the highest possible value of /. These solids are ferrimagnets with Tcs of 3.5 K and 8.5 K, respectively. 

Mn4N crystallizes with the antiperovskite structure. It is ferrimagnetic (1.2 pB) and forms solid solutions with Cu and Zn [326, 327]. The magnetic structure of Mn4N has been studied with polarized neutrons the moments of the comer Mn atoms are antiparallel to the three face-center moments [328],... 

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