High blocking temperature of Fe nanoparticles embedded in diamond thin films

We investigate the magnetic properties of Fe nanoparticles (NPs) embedded in diamond (111) thin films. The Fe NPs have body-centered cubic structures with median particle diameters in the range of 9–26 nm. Magnetization measurements revealed that they have large magnetic anisotropy and show a transition from a ferromagnetic to superparamagnetic state at a blocking temperature between 480 and around 1000 K depending on their particle diameters. These magnetic properties are well explained by coherent magnetization rotation models proposed by Stoner–Wohlfarth and Néel.