Magnetic properties and microstructure of isolated Fe-Pt nanoparticle-monolayer assembly by protective coating

In this study, a protective coating such as carbon is deposited on the Fe-Pt nanoparticle-monolayer assemblies and magnetic properties of the assemblies composed of physically isolated nanoparticles are investigated. Their microstructures are examined by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Magnetic properties are evaluated by a superconducting quantum interference device (SQUID) magnetometer in the maximum field of 50 kOe. The carbon coating suppresses coalescence of particles against high-temperature annealing. In addition, suppressing the interparticle sintering and coalescence by the protective coating of carbon reduces the offering of nucleation sites of the magnetization reversal. Furthermore, coercivity is increased by the carbon coating and the magnetization behavior of the carbon-coated assembly is particle-like.