Multi-Spin-Axis Structure for CoO

Abstract

New intensity data from CoO in the antiferromagnetic state have been obtained with a high-resolution neutron diffractometer. These improved data can be interpreted by a collinear spin structure with an angle of 27.4° between the spin axis and the $c$ axis, as compared with the older data of Roth which gave this angle as 11.5°. Alternatively a multi-spin-axis model is proposed which explains the intensity data equally well. This model is related to the collinear model B proposed by Li and has a tetragonal spin superstructure in conformity with the tetragonal crystallographic deformation below the Néel temperature.