中文摘要：

利用飞秒时间分辨泵浦-探测磁光克尔光谱对掺杂不同浓度稀土元素Tb的Heusler合金Co2FeAl（0.5）Si（0.5）（CFAS）磁性薄膜的磁各向异性和超快退磁动力学进行了研究。发现较低浓度Tb掺杂的样品出现磁化进动振荡,而较高浓度Tb的样品无磁化进动振荡,最高浓度的样品只有一个零点峰,表明不同Tb浓度的样品具有不同的磁各向异性。同时,从无进动磁化动力学曲线上观察到样品的退磁过程都是两步退磁,第一步快的退磁化过程源于过渡金属（Co Fe）的3d磁矩的超快退磁化,而第二步较慢的退磁化反映的是Tb元素的4f磁矩通过3d-5d6s-4f耦合的退磁化过程。结果表明可以通过控制掺杂Tb浓度来达到调控CFAS的磁各向异性目的。这种Tb掺杂的离面磁化的CFAS合金薄膜在自旋电子器件制作中具有巨大应用潜力。

英文摘要：

Magnetic anisotropy and ultrafast demagnetization dynamics of full-Heusler Co2 Fe Al0. 5Si0. 5（ CFAS） films doped with different concentration of rare-earth Tb are studied by using femtosecond timeresolved magneto-optical Kerr spectroscopy. It is found that the magnetization precession arises in low Tbcontent 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（ Fe Co）,while the second-step slower one is ascribed to the demagnetization of 4f moments of Tb by3d-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.