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The origin of incipient ferroelectricity in lead telluride

2016; Nature Portfolio; Volume: 7; Issue: 1 Linguagem: Inglês

10.1038/ncomms12291

2041-1723

M. P. Jiang, Mariano Trigo, Ivana Savić, Stephen Fahy, Éamonn Murray, C. C. Bray, Jesse N. Clark, Thomas Henighan, M. Kozina, Matthieu Chollet, James M. Glownia, Matthias C. Hoffmann, Diling Zhu, Olivier Delaire, Andrew F. May, B. C. Sales, Aaron M. Lindenberg, Peter Zalden, Takahiro Sato, R. Merlín, David A. Reis,

Topological Materials and Phenomena

Abstract The interactions between electrons and lattice vibrations are fundamental to materials behaviour. In the case of group IV–VI, V and related materials, these interactions are strong, and the materials exist near electronic and structural phase transitions. The prototypical example is PbTe whose incipient ferroelectric behaviour has been recently associated with large phonon anharmonicity and thermoelectricity. Here we show that it is primarily electron-phonon coupling involving electron states near the band edges that leads to the ferroelectric instability in PbTe. Using a combination of nonequilibrium lattice dynamics measurements and first principles calculations, we find that photoexcitation reduces the Peierls-like electronic instability and reinforces the paraelectric state. This weakens the long-range forces along the cubic direction tied to resonant bonding and low lattice thermal conductivity. Our results demonstrate how free-electron-laser-based ultrafast X-ray scattering can be utilized to shed light on the microscopic mechanisms that determine materials properties.