Extended Anharmonic Collapse of Phonon Dispersions in SnS
December 15, 2020
Phonon dispersion and dynamical susceptibility in SnS measured across the structural transition (Tc=880K). (a), (b) are in the low temperature Pnma phase; (c), (d) are in the high temperature Cmcm phase. (a) and (c) show first principles simulations. Inelastic neutron data collected on (b) CNCS and (d) HB-3. Intensity is plotted on a log10 scale.
Scientific Achievement
An extreme softening of an entire manifold of low energy acoustic and optic phonon branches in observed in warming SnS through a structural transition.
Significance and Impact
These strong phonon renormalization effects associated with lattice instabilities provide a new mechanism for ultra-low thermal conductivity, a desirable property for thermoelectrics, photovoltaics, and other technologically important materials.
Research Details
- Inelastic neutron scattering was used to map out the phonon excitation spectra across the structural phase transition.
- Complementary high-resolution Raman spectra were collected to probe zone-center optical modes.
- Anharmonic first-principles calculations based on density functional theory were used and to calculate the dynamical susceptibility.
“Extended anharmonic collapse of phonon dispersions in SnS and SnSe,”
Tyson Lanigan-Atkins, S. Yang, Jennifer Niedziela, Dipanshu Bansal, Andrew May, Alexander Puretzky, Jiao Lin, Daniel Pajerowski, Tao Hong, Songxue Chi, Georg Ehlers and Olivier Delaire,
Nature Communications, 11, 4430 (2020).
DOI: https://doi.org/10.1038/s41467-020-18121-4
