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

Abstract

We have experimentally investigated the correlation between the magnetoelectric coupling α 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 α was measured for the cases (a) the induced magnetization was perpendicular, α⊥, and (b) parallel, α∥, to the applied electric field. A maximum value of α⊥ = 1.01 × 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, α∥ reached a minimum value of 2.51 × 10−10 sec/m for x = 1.9.