Redistribution of Spectral Weight in Spin-1/2-Doped Haldane Chains

Abstract

We study the evolution of the dynamical spin structure factor in a spin-1 antiferromagnetic Heisenberg chain which is randomly doped with spin-1/2 moments. Using stochastic series expansion Quantum Monte Carlo simulations combined with the Maximum Entropy method, we monitor the crossover from the spin-1 chain, dominated by a single resonance at the Haldane energy, to the spin-1/2 chain with a continuum of spinon states which diverges at zero-frequency. Upon increasing the doping level, spectral weight is rapidly transferred from the Haldane peak to lower energies. If the exchange couplings between the spin-1/2 substituents and the spin-1 sites of the host are sufficiently small, finite-frequency bound states are observed below the spin gap for small doping concentrations.

RevTex, 4 pages with 4 figures

References in corpus (1)

• Random interactions and spin-glass thermodynamic transition in the hole-doped Haldane system Y${}_{2-x}$Ca${}_x$BaNiO${}_5$

Cited by in corpus (1)

• On effects of regular S=1 dilution of S=1/2 antiferromagnetic Heisenberg chains by a quantum Monte Carlo simulation