INVESTIGATIONS OF THE MAGNETIC-STRUCTURE OF THE SURFACE AND VOLUME OFALUMINUM-SUBSTITUTED SR-M TYPE HEXAFERRITES

The magnetic structure of the surface layer of single crystals of hexa gonal ferrites of the type Sr-M (SrFe12O19) in which some iron ions ar e replaced by diamagnetic Al ions is investigated, in direct compariso n with the magnetic structure in the bulk of the sample, by the method of simultaneous gamma, x-ray, and electron Mossbauer spectroscopy. It is found that under conditions of diamagnetic dilution of the magneti c lattice of hexagonal ferrites of the type Sr-M by Al ions, a layer s imilar to 200 nm thick in which the orientation of the magnetic moment s is not collinear with the direction of the moments in the bulk of th e sample is observed on the surface of SrFe10.2Al1.8O19 crystals. Thus a ''transitional'' surface layer has been observed on macroscopic fer romagnetic crystals. (C) 1998 American Institute of Physics. [S0021-36 40(98)01610-7].