paper

Deconfined pseudocriticality in a model spin-1 quantum antiferromagnet

arXiv:2307.14254 · doi:10.1088/1361-648X/ae334d

Abstract

Berry phase interference arguments that underlie the theory of deconfined quantum criticality (DQC) for spin- antiferromagnets have also been invoked to allow for continuous transitions in spin-1 magnets including a Néel to (columnar) valence bond solid (cVBS) transition. We provide a microscopic model realization of this transition on the square lattice consisting of Heisenberg exchange () and biquadratic exchange () that favor a Néel phase, and a designed -term () interaction which favors a cVBS through large-scale quantum Monte Carlo (QMC) simulations. For , this model is equivalent to the model with a Néel-cVBS transition that has been argued to be DQC through QMC. Upon turning on which brings down the symmetry to , we find multiple signatures -- a single critical point, high quality collapse of correlation ratios and order parameters, "-symmetric" cVBS histograms and lack of double-peak in order parameter histograms for largest sizes studied near the critical point -- that are highly suggestive of a continuous transition scenario. However, Binder analysis finds negative dips that grow sub-extensively that we interpret as these transitions rather being pseudocritical. This along with recent results on spin- models suggests that deconfined pseudocriticality is the more generic scenario.

Several references added. No major changes. 7 pages, 5 figures of main text. 22 pages of supplementary data. Submitted to PRL. Offered PRB. (Review exchange at https://www.dropbox.com/scl/fo/cuzciggsndwwpbznytt5g/AAi9TAQ_eGEL_AQnxU-BbbU?rlkey=0aesnku2bjv62vup1o2ps06sj&dl=0 ; names and accession code redacted)

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