Abstract / Description of output
We report that the lowest energy transverse-optic phonon in metallic SnTe softens to near zero energy at the structural transition at TC = 75 K and importantly show that the energy of this mode below TC increases as the temperature decreases. Since the mode is a polar displacement this proves unambiguously that SnTe undergoes a ferroelectric displacement below TC. Concentration gradients and imperfect stoichiometry in large crystals may explain why this was not seen in previous inelastic neutron scattering studies. Despite SnTe being metallic we find that the ferroelectric transition is similar to that in ferroelectric insulators, unmodified by the presence of conduction electrons: we find that (i) the damping of the polar mode is dominated by coupling to acoustic phonons rather than electron-phonon coupling, (ii) the transition is almost an ideal continuous transition, and (iii) comparison with density functional calculations identifies the importance of dipolar-dipolar screening for understanding this behavior.
Original language | English |
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Article number | 144101 |
Pages (from-to) | 1-5 |
Number of pages | 5 |
Journal | Physical review B |
Volume | 95 |
Issue number | 14 |
DOIs | |
Publication status | Published - 1 Apr 2017 |
Keywords / Materials (for Non-textual outputs)
- TOPOLOGICAL CRYSTALLINE INSULATOR
- LOW CARRIER CONCENTRATION
- IV-VI COMPOUNDS
- PHASE-TRANSITION
- ELECTRONIC-PROPERTIES
- NEUTRON-SCATTERING
- LATTICE-DYNAMICS
- BAND-STRUCTURE
- TIN TELLURIDE
- PBTE
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Andrew Huxley
- School of Physics and Astronomy - Chair of Physics: Quantum Ordering at Extreme Conditions
Person: Academic: Research Active