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Order by disorder from non-magnetic impurities in a two-dimensional quantum spin liquid

S. Wessel·B. Normand·M. Sigrist·S. Haas
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Abstract

We consider doping of non-magnetic impurities in the spin-1/2, 1/5-depleted square lattice. This structure, whose undoped phase diagram offers both magnetically ordered and spin-liquid ground states, is realized physically in CaV_4O_9. Doping into the ordered phase results in a progressive loss of order, which becomes complete at the percolation threshold. By contrast, non-magnetic impurities introduced in the spin liquids create a phase of weak but long-ranged antiferromagnetic order coexisting with the gapped state. The latter may be viewed as a true order-by-disorder phenomenon. We study the phase diagram of the doped system by computing the static susceptibility and staggered magnetization using a stochastic series-expansion quantum Monte Carlo technique.

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S. Wessel, B. Normand, M. Sigrist, S. Haas. 2000-07-13. Order by disorder from non-magnetic impurities in a two-dimensional quantum spin liquid. https://doi.org/10.1103/physrevlett.86.1086

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