Soft phonons and structural phase transition in superconducting Ba[subscript 0.59]K[subscript 0.41]BiO[subscript 3]
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Author(s)
Kang, H. J.
Lee, Young S.
Lynn, J. W.
Shiryaev, S. V.
Barilo, S. N.
Date Issued
March 2011
Journal
Physica C: Superconductivity
Publisher
Elsevier
Citation
Kang, H.J., Y.S. Lee, J.W. Lynn, S.V. Shiryaev, and S.N. Barilo. “Soft Phonons and Structural Phase Transition in Superconducting Ba[subscript 0.59]K[subscript 0.41]BiO[subscript 3].” Physica C: Superconductivity 471, no. 9–10 (May 2011): 303–307.
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Author's final manuscript
Abstract
We have observed a softening of phonons and a structural phase transition in a superconducting Ba[subscript 0.59]K[subscript 0.41]BiO[subscript 3] (T[subscript c] = 31 K) single crystal using elastic and inelastic neutron scattering measurements. The soft phonon occurs for the [1 1 1] transverse acoustic mode at the zone boundary. The phonon energies in this vicinity are found to continuously decrease with decreasing temperature from above room temperature. This softening stops at a temperature close to T[subscript s], where a structural phase transition from cubic to tetragonal symmetry occurs. The overall results are consistent with previous data that reported phonon softening and a (0.5, 0.5, 0.5) type superstructure in several Ba[subscript 1−x]K[subscript x]BiO[subscript 3] systems. However, we also find weaker (0.5, 0.5, 0) type superstructure peaks that reveal an additional component to the modulation. No significant change related to the superconductivity was observed for these soft phonon energies or linewidths.
MIT Department
Massachusetts Institute of Technology. Department of Materials Science and Engineering
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1016/j.physc.2011.02.010
