Odd-parity magnon spin polarization from chiral four-spin exchange in a honeycomb antiferromagnet

Bektur Murzaliev; Mikhail Titov

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arXiv · 2610.07291

Odd-parity magnon spin polarization from chiral four-spin exchange in a honeycomb antiferromagnet

Bektur Murzaliev·Mikhail Titov

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Abstract

Chiral four-spin exchange generates a momentum-dependent magnon spin in a compensated honeycomb antiferromagnet at zero magnetic field. For a Néel vector tilted by an angle $θ_0$ from the layer normal, the interaction contributes to intersublattice magnon pairing already at harmonic order, with an amplitude proportional to $\cosθ_0\sin^2θ_0$. Biaxial anisotropy mixes the two longitudinal-spin sectors, producing nonquantized mode spins that are odd in momentum, while a sublattice-exchange relation keeps the magnon energies reciprocal. A temperature gradient then induces a spin density along the Néel axis through a redistribution of magnon occupations. Reversing the four-spin coupling reverses this spin density and the mode spins without changing the magnon energies. MnPS$_3$ motivates the magnetic geometry; realizing the interaction requires a structural modification compatible with the symmetry assumptions of the model.

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Bektur Murzaliev, Mikhail Titov. 2026-10-05. Odd-parity magnon spin polarization from chiral four-spin exchange in a honeycomb antiferromagnet. https://arxiv.org/abs/2610.07291

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