Microstructure and magnetic properties of SmCo₅ thin films deposited on Cu and Pt underlayers

The microstructure of the SmCo₅ thin films sputter deposited on Cu underlayers was investigated to explain the high coercivity H_c. Energy filtered elemental map and energy dispersive x-ray spectroscopy line analysis showed that Cu diffused into the SmCo₅ layer to form a Sm(Co,Cu)₅ solid solution. Composition fluctuations with a scale length of 40 nm were found within the Sm(Co,Cu)₅ layer, which would cause the local changes in the magnetocrystalline anisotropy. The high coercivity that was observed in the continuous Sm(Co,Cu)₅ layer may be attributed to the pinning force for the magnetic domain wall motion due to the fluctuation of the magnetocrystalline anisotropy. The structure and magnetic properties of the SmCo₅ thin film deposited on a Pt underlayer were also examined for comparison.