Order-by-disorder from Schwinger bosons in a frustrated honeycomb ferromagnet

Fuente: arXiv
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Autori principali: Ralko, Arnaud, Merino, Jaime
Natura: Preprint
Pubblicazione: 2025
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author Ralko, Arnaud
Merino, Jaime
author_facet Ralko, Arnaud
Merino, Jaime
contents The cobalt-based honeycomb magnet BaCo$_2$(AsO$_4$)$_2$ (BCAO) has recently emerged as a promising platform for frustrated magnetism beyond conventional paradigms. Neutron-scattering experiments and first-principles calculations have revealed an unexpected double-zigzag (dZZ) magnetically ordered ground state, whose microscopic origin remains under active debate. Here, we revisit this problem within a ferro--antiferromagnetic $J_1$--$J_3$ Heisenberg model on the honeycomb lattice using a generalized Schwinger-boson mean-field theory (gSBMFT) that treats ferromagnetic and antiferromagnetic interactions on equal footing. This approach, combined with exact diagonalization (ED), allows us to demonstrate the emergence of the dZZ phase in a narrow parameter range, stabilized by quantum fluctuations through an order-by-disorder mechanism, in good agreement with recent density-matrix renormalization-group (DMRG) results. We further characterize the associated magnetic excitations and discuss their relevance to recent inelastic neutron-scattering (INS) measurements on BCAO.
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id arxiv_https___arxiv_org_abs_2511_16429
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Order-by-disorder from Schwinger bosons in a frustrated honeycomb ferromagnet
Ralko, Arnaud
Merino, Jaime
Strongly Correlated Electrons
The cobalt-based honeycomb magnet BaCo$_2$(AsO$_4$)$_2$ (BCAO) has recently emerged as a promising platform for frustrated magnetism beyond conventional paradigms. Neutron-scattering experiments and first-principles calculations have revealed an unexpected double-zigzag (dZZ) magnetically ordered ground state, whose microscopic origin remains under active debate. Here, we revisit this problem within a ferro--antiferromagnetic $J_1$--$J_3$ Heisenberg model on the honeycomb lattice using a generalized Schwinger-boson mean-field theory (gSBMFT) that treats ferromagnetic and antiferromagnetic interactions on equal footing. This approach, combined with exact diagonalization (ED), allows us to demonstrate the emergence of the dZZ phase in a narrow parameter range, stabilized by quantum fluctuations through an order-by-disorder mechanism, in good agreement with recent density-matrix renormalization-group (DMRG) results. We further characterize the associated magnetic excitations and discuss their relevance to recent inelastic neutron-scattering (INS) measurements on BCAO.
title Order-by-disorder from Schwinger bosons in a frustrated honeycomb ferromagnet
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2511.16429