Hopkinson Effect Study in Spinel and Hexagonal Ferrites

Abstract
The magnetic susceptibility shows a Hopkinson peak just below the Curie temperature TC when heating the selected hexagonal and spinel ferrite samples. It is proposed that this peak can be associated with a transition from stable magnetic state to super-paramagnetic relaxation above the blocking temperature up to the TC. The Hopkinson effect results are compared with SEM micrographs of both studied hexagonal and spinel ferrites.