一种非连续纳米氧化层自旋阀的显微结构研究  

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

作　　者：沈峰[1] 徐庆宇[1] 卢正启[1] 蔡建旺[1] 赖武彦[1] 张泽[1] 

机构地区：[1]中国科学院物理研究所,北京电子显微镜实验室北京100080

出　　处：《物理学报》2002年第8期1851-1855,共5页Acta Physica Sinica

基　　金：国家自然科学基金基础研究重大项目 (批准号 :19890 3 10 )资助的课题~~

摘　　要：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(3 5nm) Ni80 Fe2 0 (2nm) Ir1 7Mn83(6nm) Co90 Fe1 0 (1 5nm) NOL1 Co90 Fe1 0 (2nm) Cu(2 2nm) Co90 Fe1 0 (1 5nm) NOL2 Ta(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氧化物外 ,仍有部分铁磁性CoFe金属保留在该氧化层中 ,且贯穿该氧化层厚度区间 .覆盖于自由层之上的氧化层通过后期固相反应CoFeOx+Ta→CoFe+TaOx 形成TaOx 氧化层 (NOL2 ) .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.

关 键 词：非连续纳米氧化层 显微结构 自旋阀 高分辨电子显微学 巨磁电阻效应 多层膜 计算机 硬盘 读出磁头 

分 类 号：O482.5[理学—固体物理]