Phonon-Programmable Hidden Unconventional Magnetism in Two-Dimensional Spin-Degenerate Antiferromagnets
Abstract
Spin-degenerate antiferromagnets can host hidden unconventional magnetism in their lattice degrees of freedom. We show that coherent phonons activate this magnetism by removing the spin-layer operations that enforce equilibrium band degeneracy without changing the collinear Néel order. The frequency and polarization of a pump electric field select a resonant Γ-point optical phonon and, within a doublet, its coordinate direction. This choice fixes the residual spin-layer symmetry. In monolayer MnPSe3, an A2u mode produces i-wave splitting odd in the mass-weighted phonon coordinate Q, reversing sign under Q→−Q, whereas two orthogonal directions of the same doubly degenerate Eu doublet produce d- and s-wave splitting at a common resonance. Rotating the in-plane pump field E∥ therefore programs both the spin-splitting texture and the thermoelectric spin current, continuously tuning the response between transverse pure-spin and longitudinal spin-polarized currents. A complete classification of two-dimensional collinear spin layer groups identifies the Γ-point coordinates that remove the degeneracy-enforcing operations and activate such unconventional magnetism.
Related
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BibTeX
@misc{shen2026phononprogrammable,
title = {{Phonon-Programmable Hidden Unconventional Magnetism in Two-Dimensional Spin-Degenerate Antiferromagnets}},
author = {Xiaonong Shen and Cheng Tang and Wei Ren},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.08478},
eprint = {2609.08478},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.08478},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Phonon-Programmable Hidden Unconventional Magnetism in Two-Dimensional Spin-Degenerate Antiferromagnets
AU - Xiaonong Shen
AU - Cheng Tang
AU - Wei Ren
PY - 2026
DA - 2026/09/08
PB - arXiv
DO - 10.48550/arxiv.2609.08478
UR - https://arxiv.org/abs/2609.08478
AB - Spin-degenerate antiferromagnets can host hidden unconventional magnetism in their lattice degrees of freedom. We show that coherent phonons activate this magnetism by removing the spin-layer operations that enforce equilibrium band degeneracy without changing the collinear Néel order. The frequency and polarization of a pump electric field select a resonant Γ-point optical phonon and, within a doublet, its coordinate direction. This choice fixes the residual spin-layer symmetry. In monolayer MnPSe_3, an A_2u mode produces i-wave splitting odd in the mass-weighted phonon coordinate Q, reversing sign under Q→−Q, whereas two orthogonal directions of the same doubly degenerate E_u doublet produce d- and s-wave splitting at a common resonance. Rotating the in-plane pump field E_∥ therefore programs both the spin-splitting texture and the thermoelectric spin current, continuously tuning the response between transverse pure-spin and longitudinal spin-polarized currents. A complete classification of two-dimensional collinear spin layer groups identifies the Γ-point coordinates that remove the degeneracy-enforcing operations and activate such unconventional magnetism.
ER -