Magnetic Neutron Diffraction from Exchange-Coupled Lattices at High Temperatures

The magnetic scattering of slow neutrons from a crystal lattice with exchange coupling at temperatures much higher than the (ferromagnetic or antiferromagnetic) Curie point is investigated. The residual short-range order is shown to manifest itself in coherent and inelastic effects, which are calculated by means of an expansion in $\frac{1}{T}$. These effects can yield information on the strength of the exchange interactions, the ratio of nearest neighbor to next nearest neighbor interactions, etc. Conditions for the observability of these effects are more favorable in the antiferromagnetic case.