Magnetostriction in non-coplanar antiferromagnet in an intercalated layer compound

Chiral antiferromagnet CoX₃S₆ (X = Nb, Ta) is found to generate a large anomalous Hall effect (AHE) with a vanishing net moment, and recent neutron studies suggest a tetrahedral triple-Q spin structure below 24K [1,2]. Such a triple-Q spin structure is a short wavelength limit of skyrmion, offering a rare example of compensated but time-reversal symmetry-broken states. In this talk, we present a comprehensive magnetostriction study of CoTa3S6. We observe an onset of linear magnetostriction with c-axis magnetic field below the ordering temperature, and with a tilted magnetic field, we are able to decompose the observed dilation to the irreducible piezomagnetic tensor components. The form of our derived linear piezomagnetic tensor is consistent with the symmetry of the triple-Q spin structure and indicates that magnetostriction can be a powerful tool for identifying the symmetry of antiferromagnetic structures.

[1] Nat. Phys. 19, 961–968 (2023)

[2] Nat Commun 14, 8346 (2023)