Anomalous Lattice Dynamics near Ferroelectric Instability in PbTe
- ORNL
A recent report of highly unusual ferroelectric fluctuations in PbTe by E.S. Bozin et al. [Science 330 1660 (2010)] raises fundamental questions about the nature of underlying lattice dynamics. We show by first-principles calculations that the reported results can be attributed to abnormally large-amplitude thermal vibrations that stem from a delicate competition of dual ionicity and covalency, which puts PbTe near ferroelectric instability. It produces anomalous properties such as partially localized low-frequency phonon modes, a soft transverse optical phonon mode, and a positive temperature coefficient for the band gap. These results account for experimental findings and resolve the underlying atomistic mechanisms, which have broad implications for materials near dynamic instabilities.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences (CNMS)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1032053
- Journal Information:
- Physical Review Letters, Vol. 107, Issue 17; ISSN 0031-9007
- Country of Publication:
- United States
- Language:
- English
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