On the Paramagnetic Inelastic Scattering of Neutrons due to Ions in the Anisotropic Crystalline Field

Abstract

The paramagnetic inelastic scattering of neutrons due to ions of 3d transition elements in the anisotropic crystalline field was considered. When the orbital momentum of the paramagnetic ions is not quenched, the spin states are no longer degenerate but split into discrete levels. The transition between these levels can occur by magnetic dipole interaction of ions with neutrons, neutrons losing or gaining the corresponding energy. In the special case of FeCl₂, an antiferromagnetic crystal whose Néel temperature is 24°K, the calculation of the forward scattering cross-sections of neutrons in various temperatures and wave lengths were carried out which showed that it is possible, in the ordinary conditions, to observe the inelastically scattered neutrons, and whence to obtain an information about the energy level scheme of the atomic spin in the crystal.