Environmental Engineering Reference
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of the moments take the form:
cos( Q · R i + ϕ )
J = J sin( Q · R i + ϕ )
J =0 ,
J
J
=
(1 . 5 . 1)
while the longitudinal wave , sometimes known in the heavy rare earths
as the c-axis modulated structure or CAM, is described by
J
=
J
cos( Q · R i + ϕ ) ,
(1 . 5 . 2)
with the two other components being zero. The wave-vectors Q are along
the c -axis, and the associated wavelength 2 π/Q does not necessarily bear
any simple relationship to the lattice spacing.
Fig. 1.19. Magnetic structures of the heavy rare earths. The moments
in a particular hexagonal layer are parallel, and the relative alignments
of different planes are illustrated. From left to right; the basal-plane
ferromagnet, the helix, the cone, and the longitudinal-wave structure.
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