Jamming and Unusual Charge Density Fluctuations of Strange Metals

TL;DR

This paper explores the unusual charge density fluctuations in strange metals, proposing a jamming-like transition framework to explain their broad excitation continuum and decay behavior, challenging Fermi liquid theory.

Contribution

It introduces a phenomenological model linking charge fluctuations in strange metals to jamming-like transitions, aligning with experimental dynamical response data.

Findings

Reproduces qualitative features of charge response functions

Suggests strange metals are near a jamming-like transition

Provides a new perspective on non-Fermi liquid behavior

Abstract

The strange metallic regime across a number of high-temperature superconducting materials presents numerous challenges to the classic theory of Fermi liquid metals. Recent measurements of the dynamical charge response of strange metals, including optimally doped cuprates, have revealed a broad, featureless continuum of excitations, extending over much of the Brillouin zone. The collective density oscillations of this strange metal decay into the continuum in a manner that is at odds with the expectations of Fermi liquid theory. Inspired by these observations, we investigate the phenomenology of bosonic collective modes and the particle-hole excitations in a class of strange metals by making an analogy to the phonons of classical lattices falling apart across an unconventional jamming-like transition associated with the onset of rigidity. By making comparisons to the experimentally measured dynamical response functions, we reproduce many of the qualitative features using the above framework. We conjecture that the dynamics of electronic charge density over an intermediate range of energy scales in a class of strongly correlated metals can be at the brink of a jamming-like transition.