Magnetic Nanoparticles with Core Shell: Macroscopic Model and Coercive Field

Figure 1

Core-shell magnetic structure. The larger ellipsoid has a homogeneous magnetization 𝐈_𝐒, and the smaller ellipsoid has a homogeneous magnetization 𝐈_𝐅−𝐈_𝐒. There is a total magnetization 𝐈_𝐅−𝐈_𝐒+𝐈_𝐒=𝐈_𝐅 in the volume where smaller ellipsoid (core) is present in the larger one. The angle of the magnetization of the shell volume with the direction of the main axis is 𝜓, and the angle of the magnetization of the core with the direction of the main axis is 𝛾.