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, NiFe/Cu/NiFe/Ta/Si substrate was measured by X-ray reflectometry at Cu Kalpha, Cu Kbeta and Cu K-absorption-edge energies. The accuracy of both the Cu thickness and the interface width between the upper NiFe and the Cu layers was found to improve in the order Cu Kalpha < Cu Kbeta < Cu K-edge. The final thickness and interface width values obtained from Cu Kbeta reflectivity are in good agreement with those from the Cu K-edge. The anomalous-dispersion effect is useful in the more accurate analysis of the layered structure of transition metal multilayers because it causes a large difference in the refractive indices of specific elements near the absorption edge. The Kbeta X-rays, which can be produced from conventional X-ray sources, are also available for the accurate analysis of reflectivity measurements.
Hirano
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Hitachi Research Laboratory, Omika-cho 7-1-1, Hitachi-shi, Ibaraki 319-1292, Japan.
Usami
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Ueda
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Hoshiya
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