Static and dynamic magnetic property of MBE-grown Co_2FeAl films

摘要

In this work, the static and dynamic magnetic properties of Co_2FeAl films grown by molecular beam epitaxy (MBE) were studied by employing the magneto-optical Kerr rotation and ferromagnetic resonance (FMR) measurements. The growth temperature dependent magnetocrystalline anisotropy of MBE-grown Co_2FeAl films were first investigated by employing the rotating magneto-optical Kerr effect. Then the magnetization dynamics and Gilbert damping property for high quality Co_2FeAl films were investigated in detail by combining both the FMR and time-resolved magneto-optical Kerr rotation techniques. The apparent damping parameter was found to show strong dependence on the strength of the applied magnetic field at low-field regime, but decrease drastically with increasing magnetic field and eventually become a constant value of 0.004 at high-field regime. The inhomogeneity of magnetocrystalline anisotropy and two-magnon scattering are suggested to be responsible for the observed abnormal damping properties observed especially at low field regime. The intrinsic damping parameter of 0.004 is deduced for our highly-ordered Co_2FeAl film. Our results provide essential information for highly-ordered MBE-grown Co_2FeA film and its possible application in spintronic devices.