Inelastic neutron scattering from single crystal Zn under high pressure
- Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
- Department of Physics, Brookhaven National Laboratory, Upton, New York 11973 (United States)
Inelastic neutron-scattering experiments have been performed for single crystals of Zn under pressures up to 8.8 GPa at 300 K. The phonon modes {ital q}/{ital q}{sub max}={xi}=0.075 and {xi}=0.10 were measured in the transverse acoustic branch {Sigma}{sub 3}, where {ital q}=0 corresponds with the elastic constant {ital C}{sub 44}. The phonon energy showed a substantial hardening with increasing pressure. The experimental data below 6.8 GPa for {xi}=0.075 yield a constant Gr{umlt u}neisen mode {gamma}{sub {ital i}}={minus}ln{omega}{sub {ital i}}/ln{ital V} of 2.25 in good agreement with a previous calculation [H. Ledbetter, Phys. Status Solidi B {bold 181}, 81 (1994)]. Above 6.8 GPa, there is a very rapid increase of {gamma}{sub {ital i}} which is indicative of the presence of a giant Kohn anomaly. This rapid divergence at high pressure indicates that a phonon softening may occur at pressures higher than 8.8 GPa caused by the collapse of the giant Kohn anomaly via an electronic topological transition (ETT). In an earlier M{umlt o}ssbauer Zn study at 4 K [W. Potzel {ital et} {ital al}., Phys. Rev. Lett. {bold 74}, 1139 (1994)], a drastic drop of the Lamb-M{umlt o}ssbauer factor was observed at 6.6 GPa, which was interpreted as being due to phonon softening, indicating this ETT had occurred. This paper also compares the compressibility data for single crystal Zn and Zn powder using neutron scattering. The results were found to be similar to an earlier x-ray Zn powder experiment [O. Schulte {ital et} {ital al}., High Pressure Res. {bold 6}, 169 (1991)]. {copyright} {ital 1996 The American Physical Society.}
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 285950
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 54, Issue 2; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
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