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Title:
Chiral topological spin liquids with PEPS
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Abstract:
A simple spin-1/2 frustrated antiferromagnetic Heisenberg model (AFHM) on the square lattice - including chiral plaquette cyclic terms - was argued [Anne E.B. Nielsen et al., Nature Communications 4, 2864 (2013)] to host a bosonic Kalmeyer-Laughlin (KL) fractional quantum Hall ground state [V. Kalmeyer and R. B. Laughlin, Phys. Rev. Lett. 59, 2095 (1987)]. Here, I construct generic families of chiral projected entangled pair states (chiral PEPS) with low bond dimension (D=3,4,5) which, upon optimization, provide better variational energies than the KL ansatz. The optimal PEPS exhibits (at D=3) chiral edge modes described by the Wess-Zumino-Witten SU(2)1 model, as expected for the KL spin liquid. However, I find evidence that, in contrast to the KL state, the PEPS spin liquids have power-law dimer-dimer correlations and exhibit a gossamer long-range tail in the spin-spin correlations. I conjecture that these features are genuine to local chiral AFHM on bipartite lattices.
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