Influence of Bi on the exchange bias field of spin valve
Bi对自旋阀钉扎场的影响及机理

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.