Enhanced Strange Metallicity due to Hubbard-U Coulomb Repulsion

Abstract

We solve a model of electrons with Hubbard-$U$ Coulomb repulsion and a random Yukawa coupling to a two-dimensional bosonic bath, using an extended dynamical mean field theory scheme. Our model exhibits a quantum critical point, at which the repulsive component of the electron interactions strongly enhances the effects of the quantum critical bosonic fluctuations on the electrons, leading to a breakdown of Fermi liquid physics and the formation of a strange metal with `Planckian' ($\mathcal{O}(k_{B}T/\hslash )$) quasiparticle decay rates at low temperatures $T\to 0$. Furthermore, the eventual Mott transition that occurs as the repulsion is increased seemingly bounds the maximum decay rate in the strange metal. Our results provide insight into low-temperature strange metallicity observed in proximity to a Mott transition, as is observed, for instance, in recent experiments on certain moiré materials.

4 pages, 4 figures, 3 figures in Supplemental Material

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• Thermopower across Fermi-volume-changing quantum phase transitions without translational symmetry breaking
• Phonon Induced Energy Relaxation in Quantum Critical Metals
• Electron-phonon coupling in correlated materials: insights from the Hubbard-Holstein model