LAYERED STRUCTURE-ANALYSIS OF GMR MULTILAYERS BY X-RAY REFLECTOMETRY USING THE ANOMALOUS-DISPERSION EFFECT

As a basic layered structure for giant magnetoresistive (GMR) heads, N iFe/Cu/NiFe/Ta/Si substrate was measured by X-ray reflectometry at Cu K alpha, Cu K beta and Cu K-absorption-edge energies. The accuracy of both the Cu thickness and the interface width between the upper NiFe a nd the Cu layers was found to improve in the order Cu K alpha < Cu K b eta < Cu K-edge. The final thickness and interface width values obtain ed from Cu K beta reflectivity are in good agreement with those from t he Cu K-edge. The anomalous-dispersion effect is useful in the more ac curate analysis of the layered structure of transition metal multilaye rs because it causes a large difference in the refractive indices of s pecific elements near the absorption edge. The K beta X-rays, which ca n be produced from conventional X-ray sources, are also available for the accurate analysis of reflectivity measurements.