Anisotropic exchange coupling interaction between hard–hard magnetic grains in sintered SrFe <sub>12</sub>O <sub>19</sub> ferrites
Shuang Zhang, Chunxiang Cao, Shubing Su, Ailin Xia, Huiyan Zhang, Hailing Li, Zhiyuan Liu, Chuangui Jin
Abstract
The exchange coupling interaction in sintered magnetic materials is generally isotropic. In this study, an anisotropic exchange coupling interaction was found in the sintered oblate cylindrical SrFe<sub>12</sub>O<sub>19</sub> specimens obtained by using SrFe<sub>12</sub>O<sub>19</sub> nanopowders synthesized via a hydrothermal method. According to the Henkel plots, the exchange coupling interaction between hard-hard magnetic grains was found in both the as-pressed and the sintered specimens. However, the exchange coupling interaction can only be found in the in-plane but not in the out-of-plane direction for the sintered specimens. Through building a model of grain configuration, this anisotropy of exchange coupling interaction was ascribed to the vertically arranged plate-like SrFe<sub>12</sub>O<sub>19</sub> grains with micrometers in width but nanometers in thickness, which was confirmed by the morphology of cross section in the fractured specimens.