paper

Delocalization in harmonic chains with long-range correlated random masses

arXiv:cond-mat/0209304 · doi:10.1103/PhysRevB.68.012202

Abstract

We study the nature of collective excitations in harmonic chains with masses exhibiting long-range correlated disorder with power spectrum proportional to , where is the wave-vector of the modulations on the random masses landscape. Using a transfer matrix method and exact diagonalization, we compute the localization length and participation ratio of eigenmodes within the band of allowed energies. We find extended vibrational modes in the low-energy region for . In order to study the time evolution of an initially localized energy input, we calculate the second moment of the energy spatial distribution. We show that , besides being dependent of the specific initial excitation and exhibiting an anomalous diffusion for weakly correlated disorder, assumes a ballistic spread in the regime due to the presence of extended vibrational modes.

6 pages, 9 figures

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