Electron-Phonon Interactions and Electronic Transport in Correlated Metals and Moiré Systems

Author: Abramovitch, David Joshua

Year: 2026

Degree: Dissertation (Ph.D.)

Advisor: Bernardi, Marco

Committee Members: Fultz, Brent T.; Falson, Joseph; Chan, Garnet K.; Bernardi, Marco

Option: Applied Physics

Abstract

Interactions between electrons and lattice vibrations (phonons) give rise to transport, superconducting, and spectral properties in many classes of materials. These properties can be predicted from a microscopic understanding of the electrons, phonons, and electron-phonon coupling, but theoretical and computational hurdles limit this ability in materials with strong electronic correlations or large unit cell sizes. In Chapters 1-3, I present developments on the prediction of electron-phonon interactions and electronic transport in correlated metals. First, I will show methodology to combine first-principles electron-phonon interactions with dynamical mean-field theory electron-electron interactions into a beyond-quasiparticle description of spectra and transport. I will show applications to transport and spectral properties in the prototypical correlated metals SrVO₃ and Sr₂RuO₄, leading to an improved understanding of the respective roles of electron-phonon and electron-electron interactions in these systems. Then, I will present a method to compute the coupling of electrons to representative phonons within density functional theory plus dynamical mean-field theory. I will discuss the insights from this method on the role of orbital and phonon character, electron energy, and correlation in modifying the coupling and resulting physical properties. Transitioning to moiré systems with large unit cells, in Chapter 4, I will present a tight-binding based approximation to enable electron-phonon and transport calculations in twisted-bilayer graphene structures with over 5,000 atoms per unit cell. I will show trends in the phonon-limited resistivity as the twist angle is decreased, including the breakdown of transport properties associated with Dirac dispersion as the electronic energy scale is decreased. Taken together, this work makes promising strides and sets the stage for future developments in the study of electron-phonon physics in previously inaccessible regimes.