Antiferromagnetic structure in CoO

Possible magnetic structures of CoO, which is known to be the second kind of antiferromagnet, are discussed for the cubic phase on the basis of the extended Hubbard model including the 3d spin-orbit coupling and the intra-atomic full 3d-3d multipole interaction in the framework of the Hartree-Fock (HF) approximation. In addition to a collinear single-Q structure; a noncollinear quadruple-Q one, both of which are compatible with the neutron diffraction experiment, are obtained as stable HF solutions. The magnitude of the Co orbital magnetic moment is shown to be as large as similar to 1 mu(B).