Magnetization density and the magnetic structure of cobalt carbonate

Abstract

Single crystal diffraction measurements using both polarized and unpolarized neutrons have been made on CoCO₃ at 4.2 K. The measurements of the antiferromagnetic reflections have been used to establish a magnetic structure in which the cobalt moments lie wholly within the basal plane. This conclusion follows from a calculation of both spin and orbital scattering by the cobalt ion. This calculation is based on a model ground state wavefunction for the cobalt ion in the structure of the carbonate deduced from spectroscopic and magnetization data. The model has also been used in calculating the scattering to be expected from the weak ferromagnetic component of moment which has been measured using the polarized neutron technique. The small differences between the observed scattering and that calculated for the model can in all cases be understood from the difference density distributions as being a consequence of covalency.