Evolution of Magnetic Anisotropy With Sm Contents in Sm-Co Thin Films

In this paper, the evolution of magnetic anisotropy as a function of Sm contents in buffer-free Sm-Co thin films grown by molecular beam epitaxy is investigated. From the soft magnetic Sm₂Co₁₇ phase, the anisotropy evolves to the hard magnetic SmCo₅ phase with a distinct perpendicular anisotropy and a maximum magnetic anisotropy energy of 1.67 MJ/m³ as measured by torque magnetometry at 300 K. For SmCo₅, a saturation magnetization of 845 emu/cm³, close to the bulk single crystal value is achieved, while a squareness ratio close to unity is measured in the hysteresis curve perpendicular to the film plane. Previously grown YCo₅ and CeCo₅ thin films with perpendicular anisotropy show a considerably reduced uniaxial anisotropy as well as a reduced squareness ratio as compared to SmCo₅. These results demonstrate that the magnetic parameters of rare earth-cobalt thin films can be adapted according to the requirements of applications such as magnetic recording