Non-perturbative numerical solutions of models of strange metals with spatially random interactions, and their universal transport properties

The recently developed paradigm of spatial randomness in electron interactions in strongly correlated metals has shown great promise in explaining certain aspects of the experimental phenomenology of strange metals within the framework of large-N theories. I will describe numerically exact hybrid Monte Carlo simulations of two-dimensional metals with spatially random antiferromagnetic interactions, which are free from artificial constructions such as large-N limits. Our simulations reproduce strange metals' key experimental signature of linear-in-temperature resistivity with a universal 'planckian' transport scattering rate Γ_tr ~ 2πk_BT/h that is independent of coupling constants. We further find that strange metallicity in these systems is not associated with a quantum critical point, and instead arises from a phase of matter with gapless antiferromagnetic fluctuations that lacks long-range correlations and spans an extended region of parameter space: a feature that is also observed in several experiments. These gapless antiferromagnetic fluctuations take the form of spatially localized overdamped modes, whose presence could possibly be detected using recently developed nanoscale magnetometry methods. I will also describe signatures in the magnetic structure factor S(q, ω) of the low energy regime of spin fluctuations controlled by these localized modes, which can be measured in neutron scattering experiments. Finally, using dynamical mean field theory methods, I will show that the tendency of electrons to localize due to Hubbard-U Coulomb repulsion leads to a non-perturbative enhancement of strange metal behavior arising from spatially random antiferromagnetic interactions.