Magnetic anisotropy and ultrafast demagnetization dynamics of full-Heusler Co

2

FeAl

0.5

Si

0.5

(CFAS) films doped with different concentration of rare-earth Tb are studied by using femtosecond time-resolved magneto-optical Kerr spectroscopy. It is found that the magnetization precession arises in low Tb-content doped CFAS films

but does not arise in the higher Tb-content doped CFAS films

and only a spike occurs near zero delay time for the CFAS film with the highest Tb content. Those phenomena imply that different content of Tb has influenced the magnetic anisotropy of CFAS films. Meanwhile

ultrafast demagnetization dynamics without precession oscillation presents a two-step demagnetization process. The first-step fast demagnetization is assigned to the ultrafast demagnetization of 3d moments of transition metal (FeCo)

while the second-step slower one is ascribed to the demagnetization of 4f moments of Tb by 3d5d6s-4f coupling. The results show that the magnetic anisotropy of CFAS films can be controlled by adjusting the doping content of Tb. Tb-doping induced perpendicular magnetization CFAS magnetic films have a great potential applications in the fabrication of spintronic devices.