Effects of cobalt substitutions on the magnetoelectric coupling of M-type hexaferrite films

We have experimentally investigated the correlation between the magnetoelectric coupling alpha and Co substitutions in M-type hexaferrite films. Specifically, the following family of M-type hexaferrites materials were investigated Sr2+Cox2+Ti3-0.5x4+Fe83+O192- , where x varied from 1.2 to 3.5. The parameter alpha was measured for the cases (a) the induced magnetization was perpendicular, alpha(perpendicular to), and (b) parallel, alpha(parallel to), to the applied electric field. A maximum value of alpha(perpendicular to) = 1.01 x 10(-8) sec/m was measured for x = 1.65. This optimum value may be related to the maximum packing density of cobalt ions in octahedral sites and still maintain charge neutrality. Also, alpha(parallel to) reached a minimum value of 2.51 x 10(-10) sec/m for x = 1.9. (C) 2015 AIP Publishing LLC.