Volume 72, Number 6, December 2005
|Page(s)||1018 - 1024|
|Section||Condensed matter: electronic structure, electrical, magnetic, and optical properties|
|Published online||04 November 2005|
Anomalous optical absorption in a random system with scale-free disorder
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
Accepted: 13 October 2005
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 . This type of correlations gives rise to a phase of extended states at the band center, provided α is larger than a critical value . We show that for , the absorption spectrum is single-peaked, while an additional peak arises when , 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
© EDP Sciences, 2005
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