Coercivity and energy product of thin Sm–Co layers

We have prepared homogeneous SmCox (x=5–26) sputtered thin films of thickness 500 nm with excess Co compared to SmCo5. The purpose is to determine how any spring exchange incorporated by the excess Co improves the energy product. Films are subjected to a 30 s or 20 min anneal to crystallize the Sm–Co. In the case of both anneal methods x-ray diffraction indicated no preferential orientation of the Sm–Co film after annealing. The best value of the maximum energy product, BHmax, is 19 MG Oe (151 kJ/m3) and is found in a sample with x of 12 after a 30 s anneal at 700 °C. We also compare these results with our earlier work or Sm–Co thin films prepared initially as SmCo5/Co multilayers and find that homogeneous films tend to have a larger BHmax.