Optical absorption edge in one-dimensional conductors

TL;DR

This paper investigates the optical absorption edge in one-dimensional conductors, analyzing the frequency-dependent conductivity in models like the Hubbard model and spinless fermions, revealing a complex spectrum with a Drude peak and a pseudo-gap.

Contribution

It introduces a detailed analysis of the absorption spectrum using Bethe ansatz and conformal invariance, providing new insights into the optical properties of 1D metallic systems.

Findings

Presence of a Drude peak at zero frequency

Existence of a pseudo-gap in the absorption spectrum

Lower edge characterized by a non-classical critical exponent

Abstract

The frequency-dependent conductivity is studied for both the one-dimensional Hubbard model and a model of spinless fermions, using a selection rule, the Bethe ansatz energy eigenstates, and conformal invariance. For densities where the system is metallic the absorption spectrum has two contributions, a Drude peak at \omega = 0 separated by a pseudo-gap from a broad absorption band whose lower edge is characterized by a non-classical critical exponent. Our findings are expected to shed new light on the ``far infrared puzzle'' of metallic organic chain compounds.