Ce(27Å)/Fe($x$Å)

Figure: Normalised magnetisation vs temperature curves for Ce(27Å)/Fe($x$Å) multilayers. Cerium layer thickness is constant.

Figure 7.2 shows the scans for Ce(27Å)/Fe($x$Å) multilayers. This is another set of scans with a fixed cerium layer thickness. Here, too, the coupling can be seen to be antiferromagnetic. The 27/15 sample shows a strong increase in $\chi_{tot}$ with increasing temperature approaching $T_{N}$, indicative of antiferromagnetic coupling with a mixture of parallel and perpendicular moment alignment. This sample has a $T_{N}=125\pm5\ensuremath{\unskip\,\mathrm{K}}$. Mössbauer data show this sample to have a $20\%$ reduction in hyperfine field and has moments lying $38^{\circ}$ out of plane.

The 27/20 also shows an antiferromagnetic coupling. The data shows a much flatter curve below $T_{N}$, indicating the sample has fully spin-flopped moments. This sample has a $T_{N} = 145\pm5\ensuremath{\unskip\,\mathrm{K}}$, $20\ensuremath{\unskip\,\mathrm{K}}$ higher than that of the 27/15 sample.

At this cerium layer thickness of $27\ensuremath{\unskip\,\mathrm{\AA{}}}$ the iron layers are coupled antiferromagnetically.