Determination of spin chirality using x-ray magnetic circular dichroism

Common wisdom has it that antiferromagnetic materials show no x-ray magnetic circular dichroism (XMCD). Surprisingly, a kagome lattice that has negative spin chirality can give a nonzero XMCD signal, even though the total spin moment reduces to zero. Here, the author explains this by evoking a rule for the rotational symmetry invariance of the XMCD signal, whereby the existence of an anisotropic XMCD signal for the local magnetic atom is a necessary condition.