Mechanism of Incommensurate Magnetic Order in BaCo2(AsO4)2: Interplay of Frustrated Further-Neighbor Exchanges and Bond-Directional Anisotropy
Abstract
The microscopic mechanism governing the zero-field incommensurate magnetic order in the honeycomb cobaltate BaCo2(AsO4)2 remains a significant unresolved problem, particularly concerning the relative contributions of bond-directional Kitaev-type interactions and exchange frustration. This study investigates an extended J1−−K−−Γ−−Γ'−−J2−−J3 model, which incorporates XXZ-type exchange anisotropies on the honeycomb lattice. Nearest-neighbor parameters are constrained by ab initio electronic structure calculations. By integrating the analytical Luttinger-Tisza approach with exact diagonalization calculations under twisted boundary conditions, we delineate the classical and quantum phase diagrams across the (J2, J3) parameter space. We demonstrate that the stabilization of the experimentally observed incommensurate spiral phase, propagating along the Γ→ M direction, does not necessitate an anomalously dominant Kitaev coupling. Instead, this phase arises naturally from the synergistic interplay between exchange frustration, driven by further-neighbor couplings (J2, J3), and intermediate off-diagonal bond anisotropies ($Γ, Γ'$). In the quantum regime, we elucidate the competition between this incommensurate manifold and an out-of-plane ferromagnetic (FMz) phase, which is selectively stabilized via a quantum order-by-disorder mechanism. Our findings reconcile conflicting interpretations of the magnetic interactions in BaCo2(AsO4)2 and establish the microscopic origin and stability range of its incommensurate ground state.
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BibTeX
@misc{zare2026mechanism,
title = {{Mechanism of Incommensurate Magnetic Order in $\mathrmBaCo_2(AsO_4)_2$: Interplay of Frustrated Further-Neighbor Exchanges and Bond-Directional Anisotropy}},
author = {Mohammad-Hossein Zare and Mehdi Biderang and Hamid Mosadeq},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.00626},
eprint = {2610.00626},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.00626},
note = {CC BY-NC-SA 4.0},
}
RIS
TY - UNPB
TI - Mechanism of Incommensurate Magnetic Order in BaCo_2(AsO_4)_2: Interplay of Frustrated Further-Neighbor Exchanges and Bond-Directional Anisotropy
AU - Mohammad-Hossein Zare
AU - Mehdi Biderang
AU - Hamid Mosadeq
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2610.00626
UR - https://arxiv.org/abs/2610.00626
AB - The microscopic mechanism governing the zero-field incommensurate magnetic order in the honeycomb cobaltate BaCo_2(AsO_4)_2 remains a significant unresolved problem, particularly concerning the relative contributions of bond-directional Kitaev-type interactions and exchange frustration. This study investigates an extended J_1−−K−−Γ−−Γ'−−J_2−−J_3 model, which incorporates XXZ-type exchange anisotropies on the honeycomb lattice. Nearest-neighbor parameters are constrained by ab initio electronic structure calculations. By integrating the analytical Luttinger-Tisza approach with exact diagonalization calculations under twisted boundary conditions, we delineate the classical and quantum phase diagrams across the (J_2, J_3) parameter space. We demonstrate that the stabilization of the experimentally observed incommensurate spiral phase, propagating along the Γ→ M direction, does not necessitate an anomalously dominant Kitaev coupling. Instead, this phase arises naturally from the synergistic interplay between exchange frustration, driven by further-neighbor couplings (J_2, J_3), and intermediate off-diagonal bond anisotropies ($Γ, Γ'$). In the quantum regime, we elucidate the competition between this incommensurate manifold and an out-of-plane ferromagnetic (FM_z) phase, which is selectively stabilized via a quantum order-by-disorder mechanism. Our findings reconcile conflicting interpretations of the magnetic interactions in BaCo_2(AsO_4)_2 and establish the microscopic origin and stability range of its incommensurate ground state.
ER -