Temporal Fluctuations of Moment in Paramagnets by Neutron Diffraction

The inelastic scattering of neutrons by temporal fluctuations of spin in a paramagnet is reviewed. The scattering cross section is directly proportional to the imaginary part of the generalized frequency and wavelength-dependent susceptibility of the scattering material. For localized spins the theory of the scattering is discussed both in terms of exact solutions for the susceptibility in the few cases where this is known and in terms of the …