The magnetic anisotropy change of BaFe12-2xIrxCoxO19:: a single-crystal neutron diffraction study of the accompanying atomic and magnetic structures

In this paper, we present the atomic and magnetic structures accompanying the changer from axial to planar, of the magnetic anisotropy in BaFe12-2xIrxCoxO19 using magnetic measurements and single-crystal neutron diffraction. The magnetic measurements allowed us to determine the characteristic anisotropy field H-0 and anisotropy constants k(i) for the different stages. Our structure refinements show that the change of magnetic anisotropy in BaFe12-2xIrxCoxO19 leads, on a microscopic level, to a collective canting of the moments from 0 to 90 degrees through ferrimagnetic structures, which is in contrast to what has been observed up to now for other substituted single-crystal hexaferrites. The peculiar change of the magnetic anisotropy in BaFe12-2xIrxCoxO19 is correlated to the substitution of Fe3+ by Ir4+ on the 4e bipyramidal site. (C) 2000 Elsevier Science B.V. All rights reserved.