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Phys. Rev. B 48, 12936–12940 (1993)

Surface phonons on Bi2Sr2CaCu2O8+δ

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R. B. Phelps, P. Akavoor, and L. L. Kesmodel
Physics Department and Materials Research Institute, Indiana University, Bloomington, Indiana 47405

J. E. Demuth and D. B. Mitzi
IBM Research Division, Thomas J. Watson Research Center, Yorktown Heights, New York 10598

Received 9 July 1993; published in the issue dated 1 November 1993

We report measurements of surface optical phonons on Bi2Sr2CaCu2O8+δ with high-resolution electron-energy-loss spectroscopy (HREELS). In addition to peaks near 50 and 80 meV (403 and 645 cm-1), which have been previously observed, our loss spectra exhibit a peak at 26 meV (210 cm-1). Loss spectra were measured at temperatures from 45 to 146 K, and the temperature dependence of the peaks was found to be weak. The 50 and 80 meV peaks shift to lower frequency by ∼1.5 meV over this temperature range. All three peaks are attributed to surface optical phonons. The identification of particular bulk modes corresponding to the surface modes observed with HREELS is discussed.

© 1993 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.48.12936
DOI:
10.1103/PhysRevB.48.12936
PACS:
74.72.Hs, 68.35.Ja