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Phonon Dispersion and Kohn Anomaues in the Alloy Cu0.84Al0.16

Published online by Cambridge University Press:  21 February 2011

Henry Chou
Affiliation:
Physics Department, Brookhaven National Laboratory, Upton, N.Y. 11973
S. M. Shapiro
Affiliation:
Physics Department, Brookhaven National Laboratory, Upton, N.Y. 11973
S. C. Moss
Affiliation:
Physics Department, University of Houston, Houston, Texas 77204-5504
Mark Mostoller
Affiliation:
Solid State Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831
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Abstract

We have made detailed measurements of phonon frequencies along all high-symmetry directions on a large single crystal of Cu0.84Al0.16 at room temperature. Phonon frequencies were ascertained to better than ±0.03 meV. Inter-atomic force constants and vibrational density of states were calculated by performing a Born-von Karman analysis on the complete set of phonon dispersion curves. In contrast to the case of pure Cu, no evident Kohn anomaly (neither in the phonon dispersion itself nor in the derivatives) was observed near the expected wave vector q=2kF. The absence of Kohn anomalies in the present system could be due either to a smeared out Fermi surface or to the possibility that the electron-electron interaction which screens the inter-ionic potential is not the dominant interaction in the system; i.e. the existence of Kohn anomalies in these alloys may depend mainly on the details of the electron-phonon interaction.

Type
Research Article
Copyright
Copyright © Materials Research Society 1990

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References

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