Exchange Reflexions in Low Energy Electron Diffraction from Antiferromagnetic Nickel Oxide Crystal

The nature of exchange reflexions in low-energy electron diffraction from antiferromagnetic nickel oxide was studied in particular reference to its dependence on the diffraction condition of electrons, which was, in the present study, changed primarily by rotating the crystal at a fixed electron energy. It was pointed out that the exchange reflexions are subject to the three-dimensional diffraction conditions appropriate to the reciprocal lattice points which correspond to the magnetic structure, and also that the intensities of these weak reflexions may be favourably enhanced by the dynamical diffraction effect under the condition which involves the simultaneous presence of a strong regular reflexion.