Surface vacancy mediated pinning in maghemite NP

Surface vacancy mediated pinning of the magnetization in γ−Fe2O3 nanoparticles: A micromagnetic simulation study

Bassel Alkadour, J. I. Mercer, J. P. Whitehead, J. van Lierop, and B. W. Southern

Phys. Rev. B 93, 140411(R) (2016)

The energy landscape for a nanoparticle selected at random from the K10 enemble. Each point on the surface of the sphere represents the energy associated with the alignment of the magnetic moment. The energy is calculated using a mean field approximation based on the distribution of surface vacancies and the average angular distribution of the energy per spins at T=0 shown in Fig. 4. The energy scale associated with the color map shown on the right is given in K.