Instanton in Disordered Peierls Systems

TL;DR

This paper investigates how strong disorder fluctuations, modeled as instantons, lead to localization of electron states within the pseudogap of disordered Peierls systems, affecting their density of states and optical properties.

Contribution

It introduces a saddle-point approach to quantify the density of states and optical absorption in disordered Peierls systems considering instanton configurations.

Findings

Localized electron states are associated with instantons modeled as soliton-antisoliton pairs.

The average density of states is derived near the pseudogap.

Optical absorption coefficients are calculated at low energies.

Abstract

We study disordered Peierls systems described by the Fluctuating Gap Model. We show that the typical electron states with energies lying deep inside the pseudogap are localized near large disorder fluctuations (instantons), which have the form of a soliton-antisoliton pair. Using the ``saddle-point'' method we obtain the average density of states and the average optical absorption coefficient at small energy.