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arXiv · 2507.12588

Anisotropic Multi-Q Order in CoxTaS2

Jonathon Kruppe·Josue Rodriguez·Catherine Xu·James Analytis·Joseph Orenstein·Veronika Sunko
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Abstract

The cobalt-intercalated transition metal dichalcogenide Co$_x$TaS$_2$ hosts a rich landscape of magnetic phases that depend sensitively on $x$. While the stoichiometric compound with $x=1/3$ exhibits a single magnetic transition, samples with $x\leq 0.325$ display two transitions with an anomalous Hall effect (AHE) emerging in the lower temperature phase. Here, we resolve the spin structure in each phase by employing a suite of magneto-optical probes that include the discovery of anomalous magneto-birefringence -- a spontaneous time-reversal sensitive rotation of the principal optic axes. A symmetry-based analysis identifies the AHE-active phase as an anisotropic (2+1)\textbf{Q} state, in which magnetic modulation at one wavevector (\textbf{Q}) differs in symmetry from that at the remaining two. The (2+1)\textbf{Q} state naturally exhibits scalar spin chirality as a mechanism for the AHE and expands the classification of multi-Q magnetic phases.

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Jonathon Kruppe, Josue Rodriguez, Catherine Xu, James Analytis, Joseph Orenstein, Veronika Sunko. 2025-07-16. Anisotropic Multi-Q Order in CoxTaS2. https://arxiv.org/abs/2507.12588

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