UC Berkeley

A wide range of strongly correlated materials – including cuprates, pnictides, heavy fermion compounds, and moiré systems – exhibit linear-in-temperature resistivity, signaling a breakdown of Landau’s Fermi liquid theory. Despite substantial progress, a controlled theoretical understanding of this non-Fermi liquid metallicity remains elusive.In this dissertation, we develop a class of analytically tractable large N models that offer controlled access to strongly coupled non-Fermi liquid metallic critical points. These models retain strong correlations while enabling exact computations of key observables such as transport coefficients and out-of-time-order correlators (OTOCs) that quantify quantum chaos.In the second part of the dissertation, we turn to the phenomenon of linear magnetoresistance (LMR), another common feature of strange metals that defy standard semiclassical theory. We explain this phenomenon through a simple theory of a metal coupled to fluctuating density wave or nematic order, both of which are ubiquitously found in strange metal materials.