ESPCI web site
Thursday November 7 at 2:00 pm (Paris time)
Room Charpak, entrance building, ground floor
Unified theories of transport in solids : from crystals to glasses, and from diffusion to viscous hydrodynamics
Crystals and glasses have dramatically different properties which intrigued scientists long before the development of atomistic theories, and nowadays play a pivotal role in a variety of technologies. I will explore the quantum mechanisms that determine the macroscopic conduction properties of solids, extending established formulations1 and developing the computational framework2 to solve them. Starting from a density-matrix formalism, I will show how the semiclassical Boltzmann equation for heat transport is missing a tunneling term that becomes pivotal in disordered or defective materials3,4. I will rely on this framework to explore thermal conductivity anomalies that emerge in solids with controlled atomic disorder — e.g., crystalline bond order and nearly glassy bond geometry — showing with theory and experiments that meteoritic tridymite5 features a hybrid crystal-glass conductivity (i.e., constant from below to above the Debye temperature). Finally, I will discuss how the microscopic transport equations for electrons6 and phonons7 can be coarse-grained into mesoscopic, viscous equations ; these transcend ordinary diffusion, rationalizing the recent observation of hydrodynamic behavior and paving the way for its control and technological exploitation.
[1] M. Simoncelli, N. Marzari, and F. Mauri, Wigner Formulation of Thermal Transport in Solids, Physical Review X 12, 041011 (2022).
[2] B. P´ota, P. Ahlawat, G. Cs´anyi, and M. Simoncelli, Thermal Conductivity Predictions with Foundation Atomistic Models, arXiv:2408.00755 (2024).
[3] A. F. Harper, K. Iwanowski, W. C. Witt, M. C. Payne, and M. Simoncelli, Vibrational and thermal properties of amorphous alumina from first principles, Physical Review Materials 8, 043601 (2024).
[4] A. Pazhedath, L. Bastonero, N. Marzari, and M. Simoncelli, First-principles characterization of thermal conductivity in La PO 4 -based alloys, Physical Review Applied 22, 024064 (2024).
[5] M. Simoncelli, D. Fournier, M. Marangolo, E. Balan, K. B´eneut, B. Baptiste, B. Doisneau, N. Marzari, and F. Mauri, Temperature-invariant heat conductivity from compensating crystalline and glassy transport : from the Steinbach meteorite to furnace bricks, arXiv:2405.13161 (2024).
[6] J. Coulter, B. Rajkov, and M. Simoncelli, Coupled electron-phonon transport and viscous thermoelectric equations, manuscript in preparation (2024).
[7] J. Dragaˇsevi´c and M. Simoncelli, Viscous heat backflow and temperature resonances in extreme thermal conductors, arXiv:2303.12777 (2024).
