Effect of H ₂ sputter gas on interfacial mixing in spin valves

We introduced the use of hydrogen during the deposition of spin valves to achieve better control of interfacial mixing, especially for bottom spin valves (B-SV). The hydrogen was introduced during deposition of the CoFe or IrMn layer depending on whether it was a B-SV or a top spin valve (T-SV). The magnetoresistance ratio and Hex increased to 15% and 30%, respectively, when hydrogen (10 vol %) was introduced for a B-SV. By contrast, the hydrogen effect for a T-SV was small. Using hydrogen (10 vol %), the surface of the SV was smoother (1.01 nm) than without hydrogen (1.94 nm). In addition, the SV with hydrogen had a well-developed (111) texture and larger grains. By introducing hydrogen, we could control the microstructure and reduce the intermixing between CoFe and IrMn, especially for B-SVs.