| Abstract Scope |
A detailed view of atomic motions in solids is needed to refine microscopic theories of transport and thermodynamics, and to design improved materials. Our group uses state-of-the-art neutron and x-ray scattering techniques to probe atomic dynamics. By mapping complex spectral functions throughout reciprocal space, phonon anharmonicity and couplings to other degrees of freedom are revealed in detail. Our investigations bring direct insights into phonon scattering mechanisms, including anharmonicity, electron-phonon coupling, spin-phonon coupling, or scattering by defects and nanostructures. Our first-principles simulations enable the quantitative rationalization of these effects, for example with ab-initio molecular dynamics simulations and anharmonic renormalization at finite-temperature, and more recently with the use of machine learning accelerated simulations. This presentation will highlight results from our investigations of atomic dynamics in several classes of materials impacted by strong anharmonicity and lattice instabilities, such as halide perovskite photovoltaics, ferroelectrics / multiferroics, thermoelectrics, or superionic conductors. |