A single-crystal neutron diffraction study of the magnetic anisotropy change in Ba-hexaferrites

We performed a neutron diffraction study of the magnetic anisotropy change in BaFe12-2xMexCoxO19 (Me = Ir, Ti) single crystals. Between 200 and 300 K the two solid solutions show similar canted ferrimagnetic structures. At lo wer temperatures. the anisotropy change in the Ir4+ substituted compound ca n be seen as a collective canting of the moments from 0 degrees to 90 degre es, while for Ti4+ substituted crystals the anisotropy change has to go thr ough a multitude of complicated structures (helices, bloc arrangement). The magnetic anisotropy change appears to be principally correlated to the sub stitution on the 4e bipyramidal site in the hexaferrite structure. (C) 2000 Elsevier Science B.V. All rights reserved.