The Disorder Origin of Raman Scattering In Perovskites Single Crystals
arXiv:2208.05563 · doi:10.1103/PhysRevMaterials.7.044602
Abstract
The anharmonic lattice dynamics of oxide and halide perovskites play a crucial role in their mechanical and optical properties. Raman spectroscopy is one of the key methods used to study these structural dynamics. However, despite decades of research, existing interpretations cannot explain the temperature dependence of the observed Raman spectra. We demonstrate the non-monotonic evolution with temperature of the scattering intensity and present a model for 2nd-order Raman scattering that accounts for this unique trend. By invoking a low-frequency anharmonic feature, we are able to reproduce the Raman spectral line-shapes and integrated intensity temperature dependence. Numerical simulations support our interpretation of this low-frequency mode as a transition between two minima of a double-well potential surface. The model can be applied to other dynamically disordered crystal phases, providing a better understanding of the structural dynamics, leading to favorable electronic, optical, and mechanical properties in functional materials.
References in corpus (10)
- Raman tensor elements of
- Phonon anharmonicity, lifetimes and thermal transport in CHNHPbI from many-body perturbation theory
- Spontaneous symmetry breaking in a nonlinear double-well structure
- Dynamic Shortening of Disorder Potentials in Anharmonic Halide Perovskites
- The effects of intrinsic local distortions vs. dynamic thermal motions on the stability and band gaps of cubic oxide and halide perovskites
- Anharmonic Lattice Vibrations in Small-Molecule Organic Semiconductors
- Structural Phase Transitions
- Intrinsic local symmetry-breaking in nominally cubic paraelectric BaTiO3
- Discovery of highly-polarizable semiconductors BaZrS3 and Ba3Zr2S7
- The dielectric response of rock-salt crystals at finite temperatures from first principles