Dy/Lu superlattice

Fig. 19. Real space variation of the lattice parameter and composition for the Dy/Lu superlattice, using the X-ray data of fig. 15.

Expressions such as this interpolate between the perfect rectangular model (y=0) and an alloy (y —> oo). Figure 19 shows the result of a diffusion model analysis (Beach et al. 1993b) for a Dy/Lu superlattice, using X-ray data to determine the Dy composition and lattice spacing. 

Fig. 34. Neutnm scattering data for a Dy/Lu superlattice showing the appearance of helimagnetic order below 170 K, vdiich gives way to ferromagnetic order at low temperatnres, evidenced by increased intensity of the Bragg peak at 2.23 A. ...

As in the case of DyA shown in fig. 23, there is a definite dependence of the turn angle on relative layer thickness, and therefore on strain. Exploiting the thin-film result in fig. 7, we plot in fig. 36 the turn angle in the Dy component vs TITq and hence strain (Beach 1992). Interestingly, cUoy for Dy/Lu superlattices and the 400 A film, scale with bulk Dy, within experimental uncertainty. From these data we are able to construct the approximate phase diagram for Dy/Lu superlattices shown in fig. 37 (Beach 1992). This is an extension of the single-layer phase diagram of fig. 7. 

The rich structure of superlattice harmonics predicted by the rectangular model is mirrored by the superlattice peaks observed in the Dy/Lu sample of fig. 15. At the opposite extreme, ufien only a sinusoidal modulation of composition exists, a single... 

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