Electronic Excitations of Polar magnet (Fe_1-xZn_x)₂Mo₃O₈ Probed by Resonant Inelastic X-ray Scattering

Multiferroic materials which possess more than one ferroic order have attracted much interest because of the spontaneous coexistence of electricity and (anti)magnetism. The magnetoelectric (ME) effect is a key in designing novel electronic devices. The polar magnet Fe₂Mo₃O₈ shows not only strong ME coupling but also chemical-doping controllability of the distinct ME phases. To study the change of electronic structure with doping, we measured the high-resolution resonant inelastic X-ray scattering (RIXS) at Fe L-edge of (Fe_1-xZn_x)₂Mo₃O₈ with x = 0 and 0.125. In combination with charge-transfer multiplet calculations, our RIXS results disentangle the electronic properties of octahedral and tetrahedral Fe²⁺ and provide spectroscopic evidence that the doped Zn favors to replace tetrahedral Fe in the doped compound, in agreement with LDA+U calculations.