|Title||Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics.|
|Publication Type||Journal Article|
|Year of Publication||2014|
|Authors||CW Li, O Hellman, J Ma, AF May, HB Cao, X Chen, AD Christianson, G Ehlers, DJ Singh, BC Sales, and O Delaire|
|Journal||Physical Review Letters|
The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase space for three-phonon scattering processes, combined with the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optic ferroelectric mode.
|Short Title||Physical Review Letters|