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 Sm 2 Co 17 phase, the anisotropy evolves to the hard magnetic SmCo 5 phase with a distinct perpendicular anisotropy and a maximum magnetic anisotropy energy of 1.67 MJ/m 3 as measured by torque magnetometry at 300 K. For SmCo 5 , a saturation magnetization of 845 emu/cm 3 , 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 YCo 5 and CeCo 5 thin films with perpendicular anisotropy show a considerably reduced uniaxial anisotropy as well as a reduced squareness ratio as compared to SmCo 5 . 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.