Bi对自旋阀钉扎场的影响及机理

Influence of Bi on the exchange bias field of spin valve

实验发现将Bi插入自旋阀多层膜Ta NiFe Cu Bi(x) NiFe FeMn中可以显著地提高自旋阀的钉扎场Hex.采用XPS对Cu ,Bi元素的分布情况进行了研究 ,发现Bi的插入明显抑制了Cu原子在自旋阀的制备过程中在NiFe FeMn界面的偏聚 .进一步研究表明 :自旋阀钉扎层NiFe FeMn界面中 ,Cu原子的存在是导致自旋阀Hex小于Ta NiFe FeMn多层膜Hex的主要原因 .

The enhancement of the exchange bias field H ex of Ta/NiFe/Cu/Bi(x)/NiFe/FeMn spin valve multilayers has been observed by the use of Bi inserting layer. The composition and chemical states of Bi and Cu at sample surface were examined by X-ray photoelectron spectroscopy. The results show that the segregation of Cu atoms to the interface of NiFe/FeMn is depressed by the Bi inserting layer during the fabrication of the spin valve multilayers. We believe that the presence of Cu atoms at the interface of the pinned layer NiFe/FeMn is the main reason to cause the exchange bias field H ex of spin valve Ta/NiFe/Cu/NiFe/FeMn to be lower than that of Ta/NiFe/FeMn multilayers.