Determination of the Copper Layer Thickness in Spin Valves by Grazing Incidence X-ray Fluorescence

We show that at the standard laboratory wavelength of CuKa the scattering factors of Cu and NiosFeo2 are identical, thereby making it impossible to distinguish the boundary of the Cu spacer layer in a Cdpermalloy spin valve structure from grazing incidence x-ray reflectivity curves. Use of grazing incidence fluorescence, in conjunction with x-ray reflectivity provides sufficient information to control the Cu layer thickness. We demonstrate the technique on two spin valves with Cu spacer layers differing in thickness by a factor of 2.5. Index Terms x-ray grazing incidence fluorescence, spin valves