magnetic order with spatially alternating spin scalar chirality in overdoped CoTaS

Cho, W.*; Park, P.*; Kim, C.*; An, Y.*; 飯田 一樹*; 梶本 亮一; Matin, S.*; Sibille, R.*; Crooker, S. A.*; Park, J.-G.*

Physical Review B, 113(17), p.174410_1 - 174410_14, 2026/05

https://doi.org/10.1103/d2yy-ntns

CoTaS () exhibits a spontaneous Hall effect from spin texture in antiferromagnets, with a tetrahedral triple-Q () order and uniform spin scalar chirality. Upon Co overdoping (), it undergoes a shift in magnetic ordering vectors from to . Interestingly, the spontaneous Hall effect disappeared in the overdoped regime, which was originally attributed to the loss of order. However, a question remains whether a new type of order can exist with alternating chirality in the overdoped regime. To address this, we investigated CoTaS using inelastic neutron scattering (INS), neutron diffraction, and optical dichroism, and found that INS data and spin-wave simulations support a order with alternating chirality. Moreover, neutron diffraction data show field-independent Bragg peaks, while linear dichroism detects no in-plane anisotropy, consistent with threefold rotation symmetry. Our data support the scenario of an alternating-chirality order in CoTaS, cancelling the spontaneous Hall effect. This study highlights a combined neutron-optical approach to identify complex spin textures.