Ferromagnetic neutron peaks

Within the compounds with equivalent sites for Ce, the specific heat of Cc4Bi3 also shows two well-defined peaks (Suzuki et al. 1987). This compound lies on the borderline between regions I and II, it is actually ferromagnetic for T < 3.5 K but after undergoing a first-order transition. The entropy gain including the transition at 3.8 K is 0.8I ln2 at 20 K. The field dependence of the specific heat in this compound was compared by the authors with that of CeBg, where a quadrupolar transition was observed by neutron diffraction. 

The analysis of the polarised neutron experiment on K2NaCrFe (Fig. 9) has been completed< >. The aspherical form factor component/4(0 was shown to be particularly sensitive to the covalent spin distribution, and the shape of fi Q) supported the inference for eg spin polarization drawn from the comparison of powder neutron diffraction data and resonance data (Section VI. B). A preliminary report of the form factor determination for both tetra-hedrally and octahedrally coordinated Fe + in YaFesOis by polarized neutrons has been given ). The form factors are not the same and that for tetrahedral Fe + is contracted relative to that for octahedral Fe +, which follows closely the calculated free-ion curve. The ligand forward peak (Section VI. B) has been directly observed ) in a measurement of the critical scattering of neutrons by ferromagnetic K2CUF4. 

Fig. 3. Neutron scattering data for a 400 A Dy film grown epitaxially on Lu. The peak at 2.23 A is the (0002) peak of Dy that at 2.27 is from the Y under-layer. Note the symmetric magnetic satellites surrounding the (0002) peak. The sample is ferromagnetic at and below 95 K.

Fig. 22. Neutron scattering data from a Dy/Y superiattice. The intensity of the main Bragg peak is constant to 6K, ruling out the development of ferromagnetic order.

Fig. 35. Neutron scattering data for the Dy/Lu siq)erlattice that develops antiferromagnetic stacking of ferromagnetic Dy blocks, signalled by the peaks marked with arrows.

Fig. 47. Neutron scattering intensities of the ferromagnetic (open circles) and antifenomagnetic (solid circles) peaks for b-[Gd,9 Yj]jj. The zero-field state is ferromagnetic.

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