Universal theory of strange metals from spatially random interactions

Abstract: We consider two-dimensional metals of fermions coupled to quantum critical scalars, the latter representing order parameters or emergent gauge fields. We show that at low temperatures ($T$), such metals generically exhibit strange metal behavior with a $T$-linear resistivity arising from spatially random fluctuations in the fermion-scalar Yukawa couplings about a non-zero spatial average. We also find a $T\ln (1/T)$ specific heat, and a rationale for the Planckian bound on the transport scattering time. These results are obtained in the large $N$ expansion of an ensemble of critical metals.