Bad Metals from Fluctuating Density Waves

Luca Delacrétaz,Anna Karlsson,Blaise Goutéraux,Sean Hartnoll

doi:10.21468/scipostphys.3.3.025

Luca Delacrétaz, Anna Karlsson + Show 2 more

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https://doi.org/10.21468/scipostphys.3.3.025

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Abstract

Bad metals have a large resistivity without being strongly disordered. In many bad metals the Drude peak moves away from zero frequency as the resistivity becomes large at increasing temperatures. We catalogue the position and width of the ‘displaced Drude peak’ in the observed optical conductivity of several families of bad metals, showing that \omega_\text{peak} \sim \Delta \omega \sim k_BT/\hbarωpeak∼Δω∼kBT/ℏ. This is the same quantum critical timescale that underpins the TT-linear dc resistivity of many of these materials. We provide a unified theoretical description of the optical and dc transport properties of bad metals in terms of the hydrodynamics of short range quantum critical fluctuations of incommensurate density wave order. Within hydrodynamics, pinned translational order is essential to obtain the nonzero frequency peak.

Highlights

Bad metals are defined by the fact that if their electrical resistivity is interpreted within a conventional Drude formalism, the corresponding mean free path of the quasiparticles is so short that the Boltzmann equation underlying Drude theory is not consistent [1,2,3]
In this work we show that the hydrodynamics of phase-fluctuating charge density waves can lead to bad metallic behavior
That the low energy, non-quasiparticle, description of bad metals is strongly non-translationally invariant and momentum is absent from the hydrodynamic description [6]

Summary

Introduction

Bad metals are defined by the fact that if their electrical resistivity is interpreted within a conventional Drude formalism, the corresponding mean free path of the quasiparticles is so short that the Boltzmann equation underlying Drude theory is not consistent [1,2,3]. In this work we show that the hydrodynamics of phase-fluctuating charge density waves can lead to bad metallic behavior. A small dc conductivity despite only weak disorder is one of two key phenomenological consequences of the charge density wave scenario for bad metals.

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