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.