Helical antiferromagnetic spin structure

Lee (1964) and Landry (1967) considered the pressure influence on the turn angle

model proposed by Herpin and Meriel (1961) and F.nz (1960). The free energy of the crystal was assumed to be ... 

Fig. 5. Illustration of a helical spin structure. Ordering in each plane is ferromagnetic but the moment direction from plane to plane changes through a constant turn angle W resulting in overall antiferromagnetic behavior (after Taylor ).

Figure 4.6 (a) Schematic view of the two degenerate helical arrangements of the spins of a ID frustrated structure with antiferromagnetic next-nearest-neighbour (NNN) interactions. The angle is the one formed between the projections of two adjacent spins, drawn with different colours to... 

The rare earth metals exhibit a variety of ordered states from ferromagnetic to complicated antiferromagnetic structures collinear, spiral, helical, conical and fan structures, which can be altered by temperature, magnetic fields or by the application of pressure (Nikitin et al., 1972). These complicated arrangements of spins result from the balance in energy between magnetocrystalline anisotropy and exchange forces (Elliott, 1965). Much pressure work has been done on pure rare earth metals and alloys in the last decade especially, and measurements... 

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