Determination of the Surface Anisotropy Contribution to the Magnetic Anisotropy Field of a Nanocrystalline Barium Ferrite Powder at Various Temperatures

The temperature dependence of the average anisotropy field of a nanocrystalline barium hexaferrite powder was studied by treating remanent-magnetization curves with inclusion of thermal fluctuations. The contribution of surface anisotropy was isolated; its nonstandard temperature dependence is intimately related to the specific features of formation of near-surface regions in ultrathin particles.