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arXiv · 2608.10263

Helimagnetism from competing intra- and interchain interactions in CrBr$_2$ and CrI$_2$

John A. Schneeloch·Matthew B. Stone·Zachary Morgan·Despina Louca
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Abstract

CrBr$_2$ and CrI$_2$ are promising platforms for studying the effect of dimensionality on magnetic order, having been isolated in a 3-, 2-, and 1-dimensional form as bulk crystals, monolayers, and individual chains encapsulated in carbon nanotubes. However, the interactions that give rise to their helimagnetic order are unknown. Via inelastic neutron scattering on single crystals, we have determined the exchange interactions of these compounds from the spin wave dispersions, finding that the helimagnetic order arises primarily from competing antiferromagnetic interactions between intrachain and interchain nearest-neighbors. Single-ion anisotropy is substantial, modulating the helical spin rotation and gapping the inelastic intensity at points of branch crossings. As temperature increases, long-range order vanishes but intralayer correlations remain detectable up to at least 50 K.

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John A. Schneeloch, Matthew B. Stone, Zachary Morgan, Despina Louca. 2026-08-10. Helimagnetism from competing intra- and interchain interactions in CrBr$_2$ and CrI$_2$. https://arxiv.org/abs/2608.10263

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