Phonon densities of states of gamma-cerium and delta-cerium measured by time-of-flight inelastic neutron scattering |
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| Authors: | M.E. Manley R.J. McQueeney J.L. Robertson B. Fultz D.A. Neumann |
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| Affiliation: | 1. Beijing National Laboratory for Condensed Matter Physics , Institute of Physics, Chinese Academy of Sciences , Beijing, China;2. Department of Physics , Shanghai Jiao Tong University , Shanghai, China;3. Department of Materials Science , Fudan University , Shanghai, China |
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| Abstract: | Time-of-flight inelastic neutron scattering spectra were measured on cerium metal at temperatures near the fcc (gamma)-to-bcc (delta) transition temperature. Phonon density-of-states (DOS) curves were extracted from data acquired over a wide range of momentum transfers. A large softening of the phonon DOS was found in going from gamma-cerium to delta-cerium, and this accounts for an increase in vibrational entropy of (0.71 +/- 0.05)k B/atom. To be consistent with the latent heat of the gamma-delta transition, this increase in vibrational entropy must be accompanied by a large decrease in electronic entropy. The results not only confirm the recent discovery of a significant electronic contribution to the gamma-delta transition but also suggest that it may be twice that previously reported. |
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| Keywords: | YBa2Cu3O7 ?x magnesium oxide (MgO) interface high-resolution transmission electron microscopy |
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