Field strength- and pump fluence-dependent magnetization dynamics of the Co2FeAl films epitaxially grown on the MgO substrates

Abstract

The pump fluence- and amplitude of magnetic field-dependent demagnetization and dynamic processes are well studied in the Co2FeAl(CFA) films prepared on the MgO substrates at different temperatures by the time resolved magneto-optical Kerr effect (TR-MOKE). It is found that the demagnetization and the damping processes are strongly dependent on both the amplitude of the external fields and the pump fluences in low fields, resulting in a complex spin relaxation and damping behavior, which is mainly attributed to the non-uniform precession mode induced by the inhomogeneous magnetic anisotropy distribution and the anisotropy field competition. However, with increasing magnetic field gradually, the demagnetization and dynamic processes start to be dominated by the external field, and meanwhile the uniform spin-wave arises. More importantly, the dynamic properties are nearly independent of the amplitude of the magnetic fields and the pump fluences again. The constant damping parameter, which decreases slightly from 4.02 × 10−3 to 1.55 × 10−3 with grown temperature changing from 300 °C to 700 °C, is suggested to be an intrinsic characteristic of the CFA films, and can be attributed to the improvement of the atomic ordering and the crystal quality.