Introduction to spin dynamics. Principle of neutron magnetic scattering

Chapter V is mainly focused to present several unique phenomena initiated by the spatial dimensions as well as crystal symmetry, and sometimes uncommon crystal structure with quantum versus classical spin effects. For the readers' convenience, the introduction section is prepared by stressing how the neutron magnetic scattering provides so valuable information to understand the spin dynamics. The format of this section is as follows : the neutron magnetic scattering cross-section is given in terms of the quantum mechanical expression, which leads straightforwardly to the dynamical (wave vector) dependent magnetic susceptibility and finally the principle of the neutron spectrometers currently usable is illustrated. (author)