Depth-selective conversion-electron Mossbauer spectroscopy of the surface of Ba-M hexaferrite single crystals

The magnetic properties of a 50- to 2-nm-thick surface layer in hexagonal f errite BaFe12O19 single crystals are investigated for the first time. Measu rements are made on a conversion-electron Mossbauer spectrometer constructe d on the basis of a unique ultrahigh-vacuum magnetostatic electron analyzer of the "orange" type. An analysis of the experimental Mossbauer spectra ob tained from the surface layer of BaFe12O19 50- to 2-nm-thick single crystal s reveals that (1) the spectral line widths are close to the natural widths of Mossbauer lines and neither changes nor a set of the values of effectiv e magnetic fields, as well as a paramagnetic state of iron ions, could appe ar due to a defect such as the "surface," and (2) the experimental spectra are best described only under the assumption that the surface of a hexaferr ite BaFe12O19 single crystal contains a 2-nm-thick layer, in which the magn etic moments of iron ions are deflected through similar to 20 degrees from the crystallographic C axis along which the magnetic moments of ions locate d in the bulk of the crystal are oriented. (C) 2000 MAIK "Nauka/ Interperio dica".