Anomalous optical absorption in a random system with scale-free disorderE. 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 in final form 13 October 2005
published online 4 November 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 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.
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