"Bad Metallic Transport in a Modified Hubbard Model"

Connie H. Mousatov: Ilya Esterlis, and Sean A. Hartnoll; Physical Review Letters, 05/10/19.

Additional Authors: Ilya Esterlis, and Sean A. Hartnoll

Abstract:

Strongly correlated metals often display anomalous transport, including T-linear resistivity above the Mott-Ioffe-Regel limit. We introduce a tractable microscopic model for bad metals, by restoring in the well-known Hubbard model—with hopping t and on-site repulsion U—a “screened Coulomb” interaction between charge densities that decays exponentially with spatial separation. This interaction lifts the extensive degeneracy in the spectrum of the t = 0 Hubbard model, allowing us to fully characterize the small t electric, thermal, and thermoelectric transport in our strongly correlated model. Throughout the phase diagram we observe T-linear resistivity above the Mott-Ioffe-Regel limit, together with strong violation of the Wiedemann-Franz law and a large thermopower that can undergo sign change.