一种非连续纳米氧化层自旋阀的显微结构研究

利用高分辨电子显微学方法(HREM)研究了纳米氧化层镜面反射自旋阀多层结构Ta(35nm)Ni80Fe20(2nm)Ir17Mn83(6nm)Co90Fe10(15nm)NOL1Co90Fe10(2nm)Cu(22nm)Co90Fe10(15nm)NOL2Ta(3nm).该自旋阀的巨磁电阻(GMR)效应高达15%,较无此镜面反射纳米氧化层(NOL)的自旋阀提高近1倍,同时交换偏置场亦有所增强.高分辨显微结构分析表明,介于钉扎层与被钉扎层之间的氧化层(NOL1)并未完全氧化,即除氧化过程生成的CoFe氧化物 关键词： 自旋阀 纳米氧化层 高分辨电子显微学 巨磁电阻效应

A high resolution electron microscopy study of specular spin valves with noncontinuous nano-oxide layers

By using high resolution transmission electron microscopy (HRTEM), we have studied the microstructure of specular spin valves of Ta(3 5nm)/Ni 80 Fe 20 (2 nm)/Ir 19 Mn 81 (6 nm)/Co 90 Fe 10 (1 5 nm)//oxidation//Co 90 Fe 10 (2nm)/Cu(2 2nm)/Co 90 Fe 10 (1 5nm)//oxidation//Ta(3nm). Cross sectional HRTEM studies showed that nano oxide layer (NOL1) was not completely oxidized from the pinned CoFe layer, resulting a mixture layer of CoFe oxides and CoFe ferromagnetic metals. The ferromagnetic metals of CoFe in the NOL1 may form some ferromagnetic paths over the NOL1, allowing direct magnetic exchange coupling between IrMn and CoFe layers. No oxidized CoFe layer was found from the CoFe free layer (NOL2). This can be explained by the formation of a TaO x NOL2 layer introduced through a solid state reaction between the oxidized CoFe layer and the capping layer of Ta. The formation of the two NOLs enhanced the giant magnetoresistance ratio of the specular spin valves.