Anomalous lattice dynamics near the ferroelectric instability in PbTe

A recent report of highly unusual ferroelectric fluctuations in PbTe by E. S. Božin 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...

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Bibliographic Details
Published in:Physical review letters 2011-10, Vol.107 (17), p.175503-175503, Article 175503
Main Authors: Zhang, Yi, Ke, Xuezhi, Kent, Paul R C, Yang, Jihui, Chen, Changfeng
Format: Article
Language:English
Subjects:
COVALENCE
FLUCTUATIONS
INSTABILITY
PHONONS
PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
TEMPERATURE COEFFICIENT
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Summary:A recent report of highly unusual ferroelectric fluctuations in PbTe by E. S. Božin 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.
ISSN:0031-9007
1079-7114
DOI:10.1103/physrevlett.107.175503