Modeling of the magnetic behavior of $γ-Fe2O3$ nanoparticles mineralized in ferritin

The temperature dependent initial magnetization of $γ-Fe2O3$ (maghemite) mineralized inside ferritin protein cages has been investigated with a vibrating sample magnetometer up to 8 T. The data are fit to different magnetic models to extract values of the magnetic moment of each cluster. It is found that the application of a simple Langevin model with a first and second order term in the susceptibility greatly enhances the quality of the fit to the data suggesting that the inclusion of crystalline anisotropy is important in extracting the magnetic moment of each core.