Abstract
The local atomic structure of SnSe was characterized across its orthorhombic-to-orthorhombic structural phase transition using x-ray pair distribution function analysis. Substantial Sn displacements with a dipolar character persist in the high-symmetry high-temperature phase, albeit with a symmetry different from that of the ordered displacements below the transition. The analysis implies that the transition is neither order-disorder nor displacive but rather a complex crossover. Robust ferrocoupled SnSe intralayer distortions suggest a ferroelectriclike instability as the driving force. These local symmetry-lowering Sn displacements are likely integral to the ultralow lattice thermal conductivity mechanism in SnSe.
| Original language | English |
|---|---|
| Article number | 036101 |
| Journal | Physical Review Letters |
| Volume | 131 |
| Issue number | 3 |
| DOIs | |
| State | Published - Jul 21 2023 |
Funding
Work at Brookhaven National Laboratory (BNL), and access to the 28ID-1 beam line at NSLS-II, was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences (DOE-BES) under Contract No. DE-SC0012704. M. G. K. acknowledges partial support from DOE-BES under Grant No. DE-SC0014520. Neutron powder diffraction data were collected at BL-1B beam line of the SNS, a DOE-BES user facility operated by the Oak Ridge National Laboratory.