Abstract
We perform an exact-diagonalization study of the spin- XXZ Heisenberg antiferromagnet on the kagome lattice at finite magnetization with an emphasis on the point and in the presence of a small chiral term. Recent analytic work by Kumar et al. [K. Kumar, K. Sun, and E. Fradkin, Phys. Rev. B 90, 174409 (2014)] on the same model, using a newly developed flux attachment transformation, predicts a plateau at this value of the magnetization described by a chiral spin liquid (CSL) with a spin Hall conductance of . Such a state is topological in nature, has a ground-state degeneracy, and exhibits fractional excitations. We analyze the degeneracy structure in the low-energy manifold, identify the candidate topological states, and use them to compute the modular matrices and Chern numbers, all of which strongly agree with expected theoretical behavior for the CSL. In the limit of zero chirality, we find on most (not all) clusters that the topological invariants are still those of a CSL.
3 More- Received 22 June 2016
- Revised 21 August 2016
DOI:https://doi.org/10.1103/PhysRevB.94.134410
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