Anomalous optical absorption in a random system with scale-free disorder

TL;DR

This paper investigates how long-range correlated disorder in a one-dimensional lattice causes anomalous optical absorption features, revealing a transition linked to the Anderson localization phenomenon.

Contribution

It demonstrates the emergence of an additional absorption peak associated with the Anderson transition in a system with scale-free disorder correlations.

Findings

Single-peaked absorption spectrum for A < A_c

Additional peak appears for A > A_c

Peak location near the low-energy mobility edge

Abstract

We report on an anomalous behavior of the absorption spectrum in a one-dimensional lattice with long-range-correlated diagonal disorder with a power-like spectrum in the form S(k) ~ 1/k^A. These type of correlations give rise to a phase of extended states at the band center, provided A is larger than a critical value A_c. We show that for A < A_c the absorption spectrum is single-peaked, while an additional peak arises when A > A_c, signalling the occurrence of the Anderson transition. The peak is located slightly below the low-energy mobility edge, providing a unique spectroscopic tool to monitor the latter. We present qualitative arguments explaining this anomaly.