Laser heating and oxygen partial pressure effects on the dynamic magnetic properties of perpendicular CoFeAlO films

The impact of oxidation and laser heating on the dynamic magnetic properties of perpendicularly magnetized Co50Fe25Al25O films has been studied by time-resolved magneto-optical Kerr effect in a fslaser pump-probe setup. We find that pump laser fluence Fp can affect the effective magnetic anisotropy field and thus the precession frequency f seriously, leading to an increased dependence of effective magnetic damping factor aeff on the external field at higher fluences. Moreover, the aeff increases with increasing the oxygen partial pressure P-O2 while the uniaxial anisotropy energy Ko and Landau factor g decrease, owing to the increased proportion of superparamagnetic CoFe oxides formed by over-oxidation. By optimizing both the F-p and P-O2, the intrinsic damping factor is determined to be lower than 0.028 for the perpendicular film showing a uniaxial anisotropy energy as high as 4.3 x 10(6) erg/cm(3). The results in this study provide a promising approach to manipulate the magnetic parameters for possible applications in spintronic devices. (C) 2016 Elsevier B.V. All rights reserved.