2001/12/14 by R. P. A. Lima, Rodrigo P. A. Lima, Marcelo L. Lyra +5 · 2 citations
Physics and Astronomy · #Quantum and electron transport phenomena #Quantum many-body systems #Theoretical and Computational Physics #cond-mat.dis-nn
paper · pdf · doi:10.1103/physrevb.65.104416
7 Pages, 5 figures, to appear in Phys. Rev. B
arxiv created 2001/12/14 · openalex publication_date 2002/02/13 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We study one-magnon excitations in a random ferromagnetic Heisenberg chain with long-range correlations in the coupling constant distribution. By employing an exact diagonalization procedure, we compute the localization length of all one-magnon states within the band of allowed energies E. The random distribution of coupling constants was assumed to have a power spectrum decaying as S(k)\ensuremath∝1/k^\ensuremathα. We found that for \ensuremathα<1, one-magnon excitations remain exponentially localized with the localization length \ensuremathξ diverging as 1/E. For \ensuremathα=1 a faster divergence of \ensuremathξ is obtained. For any \ensuremathα>1, a phase of delocalized magnons emerges at the bottom of the band. We characterize the scaling behavior of the localization length on all regimes and relate it with the scaling properties of the long-range correlated exchange coupling distribution.