Nonmonotonic plasmon dispersion in strongly interacting Coulomb Luttinger liquids

TL;DR

This paper reveals that in strongly interacting one-dimensional electron systems, the plasmon energy-momentum relationship can become nonmonotonic, exhibiting maxon-roton-like features due to Coulomb interactions beyond standard approximations.

Contribution

It introduces the concept of nonmonotonic plasmon dispersion in Coulomb Luttinger liquids, extending beyond conventional bosonization theories and providing detailed theoretical analysis.

Findings

Identification of nonmonotonic plasmon dispersion in 1D Coulomb systems

Calculation of specific heat considering nonmonotonicity

Discussion of experimental systems where this phenomenon can be observed

Abstract

We demonstrate that the plasmon in one-dimensional Coulomb interacting electron fluids can develop a finite-momentum maxon-roton-like nonmonotonic energy-momentum dispersion. Such an unusual nonmonotonicity arises from the strongly interacting $1/r$ Coulomb potential going beyond the conventional band linearization approximation used in the standard bosonization theories of Luttinger liquids. We provide details for the nonmonotonic plasmon dispersion using both bosonization and RPA theories. We also calculate the specific heat including the nonmonotonicity and discuss possibilities for observing the nonmonotonic plasmon dispersion in various physical systems including semiconductor quantum wires, carbon nanotubes, and the twisted bilayer graphene at sub-degree twist angles, which naturally realize one-dimensional domain-wall states.