Recent progress in the study on phonon heat transport property of Earth's lower mantle minerals

The lattice thermal conductivities (κlat) of Earth's lower mantle (LM) minerals is a crucial parameter in the study of deep Earth dynamics and its determination is also one of the grand challenges in condensed matter physics. Here, we review recent progress on theoretical and experimental studies for theκlatunder high pressure (P) and high temperature (T) condition up to 150 GPa and 4000 K. After the critical parameters necessary to obtain converged values of theκlatare summarized, the theoreticalκlatof the LM minerals, determined through various computational methodologies, is compiled along with experimental findings. Although significant scattering is found in the experimental results at LMP,T, the quantum anharmonic lattice dynamics theory combined with the phonon Boltzmann transport theory demonstrates a clear relationship in theκlatof the end-member LM phases, MgO, MgSiO₃bridgmanite (Brg) and post-perovskite (PPv),κlatMgO>>κlatPPv>κlatBrg, and a discontinuous change in theκlatby ∼20%-50% expected across the Brg-PPv transition. Knowledge on the additional but geophysically important factors, such as the effects of iron solid solution, isotopic mass difference, and higher order crystal anharmonicity are also summarized in detail. Current problems and future perspectives are finally mentioned.