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Interfacial Electronic Charge Transfer and Density of States in Short Period Cu/Cr Multilayers

Published online by Cambridge University Press:  10 February 2011

A. F. Bello ,
T. Van Buuren ,
J. E. Klepeis  and
T. W. Barbee Jr.
A. F. Bello
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA 94551.
T. Van Buuren
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA 94551.
J. E. Klepeis
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA 94551.
T. W. Barbee Jr.
Affiliation:
Lawrence Livermore National Laboratory, Livermore, CA 94551.
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Abstract

Nanometer period metallic multilayers are ideal structures to investigate electronic phenomena at interfaces between metal films since interfacial atoms comprise a large atomic fraction of the samples. The multilayers studied were fabricated by magnetron sputtering and consist of bilayers from 1.9 nm to 3.3 nm. X-ray diffraction, cross-section TEM and plan-view TEM show the Cu layers to have a BCC structure Cu in contrast to its equilibrium FCC structure. The electronic structure of the Cu and the Cr layers in several samples of thin Cu/Cr multilayers were studied using x-ray absorption spectroscopy (XAS). Total electron yield was measured and used to study the white lines at the Cu L2 and L3 absorption edges. The white lines at the Cu absorption edges are strongly related to the unoccupied d-orbitals and are used to calculate the amount of charge transfer between the Cr and Cu atoms in interfaces. Analysis of the Cu white lines show a charge transfer of 0.026 electrons/interfacial Cu atom to the interfacial Cr atoms. In the Cu XAS spectra we also observe a van Hove singularity between the L2 and L3 absorption edges as expected from the structural analysis. The absorption spectra are compared to partial density of states obtained from a full-potential linear muffin-tin orbital calculation. The calculations confirm the presence of charge transfer and indicate that it is localized to the first two interfacial layers in both Cu and Cr.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 524: Symposium V – Application of Synchrotron Radiation Techniques…IV , 1998 , 285
Copyright
Copyright © Materials Research Society 1998

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References

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