This title appears in the Scientific Report : 2019

##### Common acoustic phonon damping in inorganic and hybrid lead halide perovskites
Personal Name(s): Songvilay, M. (Corresponding author) / / / / / / / / / / / / / Streumethoden; JCNS-2 JCNS-ILL; JCNS-ILL JARA-FIT; JARA-FIT Streumethoden; PGI-4 Physical review materials, 3 (2019) S. 093602 College Park, MD APS 2019 10.1103/PhysRevMaterials.3.093602 Journal Article Jülich Centre for Neutron Research (JCNS) Materials and Processes for Energy and Transport Technologies Quantum Condensed Matter: Magnetism, Superconductivity Controlling Collective States Controlling Collective States OpenAccess OpenAccess Publikationsportal JuSER
Please use the identifier: http://dx.doi.org/10.1103/PhysRevMaterials.3.093602 in citations.
Please use the identifier: http://hdl.handle.net/2128/22867 in citations.
 The acoustic phonons in the organic-inorganic lead halide perovskites have been reported to have anomalously short lifetimes over a large part of the Brillouin zone. The resulting shortened mean free paths of the phonons have been implicated as the origin of the low thermal conductivity. We apply neutron spectroscopy to show that the same acoustic phonon energy linewidth broadening occurs in the fully inorganic CsPbBr$_{3}$ by comparing the results on the organic-inorganic CH$_{3}$NH$_{3}$PbCl$_{3}$. We investigate the critical dynamics near the three zone boundaries of the cubic $Pm\overline{3}m$ Brillouin zone of CsPbBr$_{3}$ and find energy and momentum broadened dynamics at momentum points where the Cs-site ($A$-site) motions contribute to the cross section. Neutron diffraction is used to confirm that both the Cs and Br sites have unusually large thermal displacements with an anisotropy that mirrors the low temperature structural distortions. The presence of an organic molecule is not necessary to disrupt the low-energy acoustic phonons at momentum transfers located away from the zone center in the lead halide perovskites and such damping may be driven by the large displacements or possibly disorder on the $A$ site.