Magnetotransport in a Model of a Disordered Strange Metal

We engineer a microscopic model of two-dimensional itinerant electrons locally and randomly scattering off point-like impurities which are described by Sachdev-Ye-Kitaev (SYK) models. For a particular choice of the scattering interaction, this model realizes a controlled description of a diffusive marginal Fermi liquid without momentum conservation, which has a linear-in-T resistivity. By tuning the strength of the scattering interaction relative to the bandwidth of the itinerant electrons, we can additionally obtain a finite-T crossover to a fully incoherent regime that also has a linear-in-T resistivity. We describe the magnetotransport properties of this model. We then consider a macroscopically disordered sample with domains of such marginal Fermi liquids with varying electron and impurity densities. Using an effective medium approximation, we obtain a macroscopic electrical resistance that scales linearly in the applied transverse magnetic field B at large B. The resistance also scales linearly in T at small B, and as T f(B/T) at intermediate B. We consider implications for recent experiments reporting linear transverse magnetoresistance in the strange metal phases of the pnictides and cuprates.