The influence of grain morphology and easy axis orientation on the coercivity of Sm(Co_0.9Cu_0.1)₅ thin films

Sm(Co_0.9Cu_0.1)₅ single-layer thin films and Sm(Co_0.9Cu_0.1)₅/Fe₂Co exchange coupled bilayer films with c-axis in the plane (IP) and out of the plane (OOP) orientations were prepared on MgO and Al₂O₃ single crystalline substrates by magnetron sputtering. Clear relationship between the grain morphology and coercivity was observed for the Sm(Co_0.9Cu_0.1)₅ single-layer films. We found the thermal stability of coercivity is largely influenced by the c-axis orientation because the c-axis IP geometry lowers magnetostatic effect that plays an increasing role at elevated temperature. In Sm(Co_0.9Cu_0.1)₅/Fe₂Co bilayer films with the two c-axis geometries, the coercivity show larger dependence on the thickness of the Fe₂Co layer for the c-axis IP geometry due to the energetically unfavorable magnetostatic coupling between hard/soft-magnetic layers, which is supported by micromagnetic simulations.