Date:
Thu, 16/06/2022 - 11:00 to 12:00
Location:
Los Angeles Bld., Jerusalem, Israel
Abstract:
In the past several years, my group investigated the structural dynamics of halide, oxide, and
sulfide perovskite crystals using Raman scattering. The perovskite crystal's structural dynamics
are fascinating because they exhibit a plethora of anharmonic effects such as soft modes,
order-disorder phase transitions, and local fluctuations. Such effects have significant
implications on the electronic properties (e.g. dielectric response, carrier lifetimes, and carrier
mobilities) of the crystals, especially at finite temperatures where these properties are
invariably relevant. Importantly they may lead to the relaxation of the symmetry-based
selection rules for Raman scattering. On the one hand, the resulting Raman spectra are
difficult to interpret; on the other, they are rich in information regarding the crystal
properties.
In this talk, I will review our journey to unlock the mysteries of perovskite structural dynamics using Raman spectra. First, I will demonstrate and discuss a common discrepancy between x-ray diffraction data showing perfect single crystals and Raman data showing disorder. Next, I will explain how we use generalized scattering models to settle this discrepancy. Finally, I will show that the intensity of the scattered light, an underused experimental observable, can be utilized to learn much regarding crystal properties such as dielectric response.
In the past several years, my group investigated the structural dynamics of halide, oxide, and
sulfide perovskite crystals using Raman scattering. The perovskite crystal's structural dynamics
are fascinating because they exhibit a plethora of anharmonic effects such as soft modes,
order-disorder phase transitions, and local fluctuations. Such effects have significant
implications on the electronic properties (e.g. dielectric response, carrier lifetimes, and carrier
mobilities) of the crystals, especially at finite temperatures where these properties are
invariably relevant. Importantly they may lead to the relaxation of the symmetry-based
selection rules for Raman scattering. On the one hand, the resulting Raman spectra are
difficult to interpret; on the other, they are rich in information regarding the crystal
properties.
In this talk, I will review our journey to unlock the mysteries of perovskite structural dynamics using Raman spectra. First, I will demonstrate and discuss a common discrepancy between x-ray diffraction data showing perfect single crystals and Raman data showing disorder. Next, I will explain how we use generalized scattering models to settle this discrepancy. Finally, I will show that the intensity of the scattered light, an underused experimental observable, can be utilized to learn much regarding crystal properties such as dielectric response.