Circular Dichroism in Resonant Photoelectron Diffraction as a Direct Probe of Sublattice Magnetization in Altermagnets

Altermagnets are a new class of magnetic materials that are promising for spintronics technology. Here it is shown that in altermagnets, the circular dichroism (CD) in resonant photoelectron diffraction (RPED) contains a time-reversal odd signal, which provides a direct probe of the sublattice magnetization. RPED calculations are performed for MnTe at the Mn L$_{2,3}$-edge resonance, using a combination of atomic multiplet and multiple scattering theory. A large magnetic CD is found for light helicity parallel to the Néel vector. This signal has the same angular distribution as the difference between the structural RPED of the two magnetic sublattices and its amplitude is approximately proportional to the X-ray magnetic CD in absorption of a single sublattice, thus providing a direct probe of the local magnetic moments.