Omer Yaffe1
Weizmann Institute1
<br/>In the past several years, my group investigated the structural dynamics of halide, oxide, and sulfide perovskite crystals by means of Raman scattering.<br/>The structural dynamics of the perovskite crystals are fascinating because they exhibit a plethora of anharmonic effects such as soft modes, order-disorder phase transitions, and local fluctuations.<br/>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 truly relevant.<br/>Importantly they may lead to the relaxation of the symmetry-based selection rules for Raman scattering.<br/>On one hand, the resulting Raman spectra are difficult to interpret, on the other, they are rich in information regarding the crystal properties.<br/><br/><br/>In this talk, I will review our journey to unlock the mysteries of perovskite structural dynamics, using Raman spectra.<br/>First, I will demonstrate and discuss a common discrepancy between x-ray diffraction data showing perfect single crystals and Raman data showing disorder.<br/>Next, I will explain how we use generalized models of scattering to settle this discrepancy.<br/>Finally, I will show that the intensity of the scattered light, which is an underused experimental observable, can be utilized to learn much regarding crystal properties such as dielectric response.