LAYERED SYNTHETIC MICROSTRUCTURES: IMPORTANCE OF A COMBINED X-RAY STANDING WAVE AND X-RAY REFLECTIVITY ANALYSIS

摘要

Layered synthetic microstructures consisting of thin layers of alternating elements or compounds have unique structural, electronic and magnetic properties with a wide range of applications. For such multilayer systems it is important to correlate the measured properties with structure and composition so that preparation techniques can be optimized to yield high performance materials. For magnetic multilayers where alternating layers are magnetic and nonmagnetic materials, a small amount (even a few percent) of magnetic impurity (either from the magnetic layers or external) in the nonmagnetic layer can change the magnetic coupling and magnetoresistance significantly. Determination of such small concentrations by X-ray reflectrometry is often very difficult. Layer composition is more accurately determined by X-ray standing wave (XSW) analysis, while interface roughness is more accurately determined by the X-ray reflectivity (XRR) technique. It is shown that for periodic multilayers, a combined XSW and XRR analysis provides more accurate compositional and microstructural information overcoming the deficiencies of the individual techniques.