Effect of annealing treatments on the magnetic properties of FeCo/Cu core shell nanostructures

The core shell structured, soft magnetic materials composed of FeCo core and copper as the shell were synthesized at room temperature electrochemically in an aqueous copper sulfate medium. The morphology, grain size, lattice strain and magnetic properties of the samples were characterized by using atomic force microscopy, x-ray diffraction, and vibrating sample magnetometer. The effect of thermal treatments on the magnetic properties of the FeCo/Cu core shell was studied. It has been found that all the samples are ferromagnetic at room temperature, however, a remarkable improvement in soft magnetic property has been achieved in the sample after compaction and subsequent magnetic annealing. The highest saturation magnetization of 164 emu/g was attained in the magnetically annealed compact sample which is close to the theoretical value of bulk FeCo magnets. The curie temperature of the compact samples was found to be 906 degrees C.