MS28-P03 On Magnetic and Crystal Structures of NiO, MnO Pomjakushin Vladimir (Lab. for Neutron Scattering, Paul Scherrer Institute, Villigen, Switzerland)email: vladimir.pomjakushin@psi.ch

Since the first neutron diffraction studies of manganese and nickel monoxides [1] the interest to the magnetic and crystal structures of MnO and NiO is kept up, see e.g. experimental study [2] and theoretical first principal calculations [3] and references cited therein. It is well established experimentally that below N ́eel temperature the crystal structure is metrically lowered in symmetry from cubic Fm̄3to rhombohedral R̄3m, or might be to monoclinic one. However, the allowed by symmetry monoclinic distortions from rhombohedral R̄3m-metric are very small and the explicit monoclinic splittings of the diffraction peaks have not been experimentally observed. We analyse in full details all possible magnetic crystallographic models metrically compatible with the experiment by using isotropy subgroup representation approach based on the propagation vector star. The models (some not previously considered) are compared with the high resolution and high intensity diffraction data measured at the HRPT diffractometer at Swiss neutron spallation source SINQ.

References:

[1] C. G. Shull, W. A. Strauser, and E. O. Wollan, (1951), Physical Review 83, 333,

[2] S. Lee, Y. Ishikawa, P. Miao, S. Torii, T. Ishigaki, and T. Kamiyama, (2016) Physical Review B 93 064429.

[3] J. S. Lim, D. Saldana-Greco, and A. M. Rappe, (2016) Physical Review B 94, 165151.
Keywords: magnetic, structure, symmetry,