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

E. Díaz; A. Rodríguez; F. Domínguez-Adame; V. A. Malyshev

doi:10.1209/epl/i2005-10321-x

All issues

Volume 72 / No 6 (December 2005)

Europhys. Lett., 72 6 (2005) 1018-1024

Abstract

Issue		Europhys. Lett. Volume 72, Number 6, December 2005


Page(s)		1018 - 1024
Section		Condensed matter: electronic structure, electrical, magnetic, and optical properties
DOI		https://doi.org/10.1209/epl/i2005-10321-x
Published online		04 November 2005

Europhys. Lett., 72 (6), pp. 1018-1024 (2005)

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

E. Díaz¹, A. Rodríguez², F. Domínguez-Adame¹ and V. A. Malyshev³

¹ GISC, Departamento de Física de Materiales, Universidad Complutense E-28040 Madrid, Spain
² GISC, Departamento de Matemática Aplicada y Estadística, Universidad Politécnica E-28040 Madrid, Spain
³ Institute for Theoretical Physics and Materials Science Centre University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands

Received: 18 July 2005
Accepted: 13 October 2005

Abstract

Optical spectroscopy usually fails in detecting localization-delocalization (Anderson) transitions. We report on an anomalous behavior of the absorption spectrum in a one-dimensional lattice with long-range correlated diagonal disorder, having a power-like spectrum $S(k) \sim 1/k^{\alpha}$ . This type of correlations gives rise to a phase of extended states at the band center, provided α is larger than a critical value $\alpha_c$ . We show that for $\alpha < \alpha_c$ , the absorption spectrum is single-peaked, while an additional peak arises when $\alpha > \alpha_c$ , signaling 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. 

PACS: 78.30.Ly – Disordered solids / 71.30.+h – Metal-insulator transitions and other electronic transitions / 71.35.Aa – Frenkel excitons and self-trapped excitons

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