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Spin-gap physics, ground state degeneracy, and bound states on the depleted kagome lattice

C. Hooley·A. M. Tsvelik
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Abstract

We analyse the antiferromagnetic spin-1/2 Heisenberg model on a depleted kagome lattice, where some bonds have been reduced to exchange integral J_2 << J_1. The fully depleted system consists of 1D chains, each with a doubly degenerate singlet-pair ground state and a spectral gap (like the Majumdar-Ghosh model). There are localised and itinerant low-energy excitations. The modes from the lowest branch of excitations are incapable of lifting the 2D system's ground state degeneracy at finite J_2/J_1 << 1. Low-energy excitations of the 2D system are dominated by coherently propagating bound states of the 1D excitations.

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C. Hooley, A. M. Tsvelik. 1999-10-20. Spin-gap physics, ground state degeneracy, and bound states on the depleted kagome lattice. https://arxiv.org/abs/cond-mat/9903044

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