Dy/Y superlattice

Fig. 9. Magnetic phase diagram for 6-axis Dy/Y superlattices and 6-axis films up to 1 pm thick. The lower surface (solid lines) separates the helimagnetic and fan phases, the upper surface (dashed lines) marks the saturation fields. The bulk limits are shown in the foreground.

Fig. 24. Magnetic moment per Dy atom fi>r a Dy/Y superlattice (a) deduced from the helimagnetic peaks (b) shows that a residual, incoherent ferromagnetic intensity is present, accounting for the missing moment.

Fig. 26. Evolution of the helimagnetic peaks in a field for a Dy/Y superlattice at 10 K and at 130 K. Note loss of coherence at 130 K.

Fig. 44. Neutron scattering scans for a 6-axis Dy/Y superlattice. Solid circles, scan through nuclear siqjerlattice peaks open circles, scan across the helimagnetic peak. The absence of sharp supeilattice harmonics indicates that the order is confined to each Dy layer.

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. 

In addition to the simple superlattice structures described above, a number of more complex structures have been fabricated. They include Fibonacci sequences of Gd and Y (Majkrzak et al. 1991) and lanthanide/lanthanide superlattices with competing anisotropies, such as Ho/Er (Simpson et al. 1994), Gd/Dy, and DyATDy (Camley et al. 1990). We refer the reader to the original sources for details. 

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