A high resolution electron microscopy study of specular spin valves with noncontinuous nano-oxide layers
一种非连续纳米氧化层自旋阀的显微结构研究

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.