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 Sr 2 + Co x 2 + Ti 3 - 0.5 x 4 + Fe 8 3 + O 19 2 -, 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.