Magnetic properties of Fe3C ferromagnetic nanoparticles encapsulated in carbon nanotubes

The low-temperature dependences of magnetic characteristics (namely, the coercive force H (c) , the remanent magnetization M (r) , local magnetic anisotropy fields H (a), and the saturation magnetization M (s) ) determined from the irreversible and reversible parts of the magnetization curves for Fe3C ferromagnetic nanoparticles encapsulated in carbon nanotubes are investigated experimentally. The behavior of the temperature dependences of the coercive force H (c) (T) and the remanent magnetization M (r) (T) indicates a single-domain structure of the particles under study and makes it possible to estimate their blocking temperature T (B) = 420-450 K. It is found that the saturation magnetization M (s) and the local magnetic anisotropy field H-a vary with temperature as similar to T-5/2.