Magnetic Helices in Ba-(TiCo)-Ferrite Determined by the RXMS Method

Introduction The crystal structure of hexagonal M-type barium ferrite BaFe12O19 has a sequence of spinel fcc blocks of (Fe6O8) 2+ and hcp blocks of (BaFe6O11) , where there are a tetrahedral 4f1, a bipyramidal 2b, octahedral 2a, 4f2 and 12k sites. Although the magnetism is strongly uniaxial along the c axis [1], the substitution of Fe ions by different-valence ions such as Ti and Co results in the reduction of the axial anisotropy [2,3]. Since the substitution weakens the anisotropy, we aim to determine the magnetic structure with the spin orientations for the five cation sites of BaCoTiFe10O19 by a combination study of site-occupancy refinements, x-ray magnetic circular dichroism (XMCD) and resonant x-ray magnetic scattering (RXMS).