  X-ray magnetic circular dichroism (XMCD) is generally not observed for
antiferromagnetic (AFM) states because XMCD signals from the antiparallelly
coupled spins cancel each other. In this letter, we theoretically show the
presence of an XMCD signal from compensated two-dimensional triangle AFM
structures on a Kagome lattice. The calculation reveals the complete
correspondence between the XMCD spectra and the sign of the spin chirality: the
XMCD signal only appears when the spin chirality is negative. This XMCD signal
originates from the different absorption coefficients of the three sublattices
reflecting different charge density anisotropies and directions of spin and
orbital magnetic moments.
