Hubbard U enhancement of planckian scattering under exact random-Yukawa treatment

Determine whether introducing a repulsive onsite Hubbard interaction U into the two-dimensional spin-fermion model with spatially random Yukawa coupling, treated exactly via hybrid Monte Carlo without replica averaging, enhances the planckian transport coefficient α0 in the linear-in-temperature DC scattering rate, analogous to the enhancement reported in dynamical mean-field theory for replica-averaged random Yukawa interactions.

Background

The paper studies a realistic two-dimensional spin-fermion model with spatially random antiferromagnetic Yukawa interactions and solves it exactly using large-scale hybrid Monte Carlo without resorting to large-N limits or replica averaging. In this framework, the authors find a strange metal phase exhibiting linear-in-temperature resistivity and planckian transport with a coefficient α0 ≈ 0.4 that is independent of the coupling strength of the random Yukawa interaction.

A paper using dynamical mean-field theory (DMFT), where random Yukawa interactions were treated via replica averaging, reported that adding a repulsive Hubbard interaction U strongly enhances the planckian coefficient α0, albeit in a strange metal realized only at a quantum critical point. The present work raises the question of whether such an enhancement of α0 by U persists when the random Yukawa interactions are treated exactly, motivating future exact simulations of the spin-fermion model with a Hubbard U term.