Recent studies suggest that the candidate Kitaev magnet ${\mathrm{Na}}_2{\mathrm{Co}}_2{\mathrm{TeO}}_6$ possesses novel triple-$\mathbf{q}$ magnetic order instead of conventional single-$\mathbf{q}$ zigzag order. Here we present dedicated experiments in a search for distinct properties expected of the triple-$\mathbf{q}$ order, namely, insensitivity of the magnetic Bragg intensities to weak $C_3$ symmetry-breaking fields and fictitious magnetic fields generated by the spin vorticity. In structurally pristine single crystals, we show that $C_3$ symmetry-breaking in-plane uniaxial strains do not affect the order’s magnetic neutron diffraction signals. We further show that $c$-axis propagating light exhibits large Faraday rotations in the ordered state due to the spin vorticity, the sign of which can be trained via the system’s ferrimagnetic moment. These results favor the triple-$\mathbf{q}$ order in ${\mathrm{Na}}_2{\mathrm{Co}}_2{\mathrm{TeO}}_6$ and reveal its unique emerging behavior.

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• Faraday effect
• Magnetic order
• Antiferromagnets
• Ferrimagnets
• Honeycomb lattice
• Layered crystals
• Noncollinear magnets
• Strongly correlated systems
• Magneto-optical Kerr effect
• Neutron diffraction