表面活性剂Bi对自旋阀多层膜交换耦合场的影响及其微结构分析

采用磁控溅射方法制备了Ta(10nm)/NiFe(8nm)/Cu(2.6nm)/NiFe(3.6nm)/FeMn(9nm)/Ta(10nm)自旋阀多层膜.在Cu/NiFe界面沉积适量厚度的Bi原子能够有效地提高交换耦合场,沉积过量的Bi原子会导致交换耦合场下降.X射线光电子能谱分析结果表明:沉积在Cu/NiFe界面的Bi原子可以有效地抑制Cu原子在NiFe层表面的偏聚;当沉积过量的Bi原子时,Bi原子会进一步迁移到FeMn中,形成杂质,从而破坏了FeMn的反铁磁性,使交换耦合场降低.

Influences of surfactant Bi on the exchange coupling field and microstructure of spin-valve multilayers

Ta(10 nm)/NiFe(8 nm)/Cu(2.6 nm)/NiFe(3.6 nm)/FeMn(9 nm)/Ta(10 nm)spin valve multi-layers were prepared by magnetron sputtering.It is found that an enhancement of exchange coupling field can be achieved by depositing a Bi layer with appropriate thickness at the Cu/NiFe interface.The results of X-ray photoelectron energy spectra show that the segregation of Cu atoms to the surface of the NiFe layer can be depressed effectively.Excessive Bi atoms can further migrate to the FeMn layer,which may produce lots of impurities.Consequently the ferromagnetism of the FeMn layer is damaged and the exchange coupling field is decreased.