Ta/NiFe/Cu/NiFe/FeMn/Ta自旋阀多层膜的X射线光电子能谱的研究

Studies of X-ray Photoelectron Spectroscopy of Spin-valve Multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta

实验表明Ta NiFe FeMn Ta多层膜的交换耦合场(Hex)要大于Ta NiFe Cu NiFe FeMn Ta自旋阀多层膜中的Hex。为了寻找其原因,用X射线光电子能谱(XPS)研究了Ta(12nm) NiFe(7nm),Ta(12nm) NiFe(7nm) Cu(4nm)和Ta(12nm) NiFe(7nm) Cu(3nm) NiFe(5nm)3种样品,研究结果表明,前两种样品表面无任何来自下层的元素偏聚;但在第3种样品最上层的NiFe表面上,探测到从下层偏聚上来的Cu原子。我们认为:Cu在NiFe FeMn层间的存在是Ta NiFe Cu NiFe FeMn Ta自旋阀多层膜的Hex低于Ta NiFe FeMn Ta多层膜Hex的一个重要原因。

The experimental results show that the exchange coupling field (Hex) of NiFe/FeMn for Ta/NiFe/FeMn/Ta multilayers is higher than that for the spinvalve multilayers Ta/NiFe/Cu/NiFe/FeMn/Ta. The composition and chemical states at the surface of Ta(12 nm)/NiFe(7 nm), Ta(12 nm)/NiFe(7 nm)/Cu(4 nm) and Ta(12 nm)/NiFe(7 nm)/Cu(3 nm)/NiFe(5 nm) were studied by using the Xray photoelectron spectroscopy (XPS). The results show that no element from underlayer floats out or segregates to the surface of Ta(12 nm)/NiFe(7 nm), Ta(12 nm)/NiFe(7 nm)/Cu(4 nm). However, Cu atoms segregate to the surface of Ta(12 nm)/NiFe(7 nm)/Cu(3 nm)/NiFe(5 nm) multilayers, i.e. to the NiFe/FeMn interface for Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers. The authors believe that the presence of Cu atoms at the interface of NiFe/FeMn is one of the important factors which will cause the exchange coupling field Hex of Ta/NiFe/FeMn/Ta multilayers to be higher than that of Ta/NiFe/Cu/NiFe/FeMn/Ta multilayers.