Role of the Size, Temperature and Field Factors in the Magnetic State Formation of the BaO · 6 Fe2O3 Fine System

Abstract

The magnetic state of the system of the highly anisotropic BaO · 6 Fe2O3 nanocrystals was investigated. The samples have been obtained using a cryochemical technology. The transition of particles into a superparamagnetic state is found and the role of an external magnetic field in its realization is demonstrated. The H–T diagram is obtained in the interval 4.2 to 723 K, where some regions not inherent in the macroscopic object are found. These are, in particular, due to both the broad distribution of anisotropy fields and the breaking of magnetic structure in the near‐surface zone of particles. Relatively large intervals of magnetic fields and temperatures are found where processes of the reversible rotation of the magnetization vector of particles play a significant role.