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

Stefan Wessel·Stephan Haas
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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.

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Stefan Wessel, Stephan Haas. 2001-06-19. Redistribution of Spectral Weight in Spin-1/2-Doped Haldane Chains. https://doi.org/10.1103/physrevb.65.132402

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