RIXS excitations of polar magnet Fe₂Mo₃O₈

Cross control of magnetization (electric polarization) by an external electric (magnetic) field, i.e. magnetoelectric (ME) effect, is a key in designing novel multiferroic devices. The polar magnet Fe₂Mo₃O₈ has been demonstrated to be a promising multiferroic material recently. The ME coupling is not only strong but also compositionally tunable. Upon Zn doping higher than 12.5 %, the antiferromagnetic ground state becomes ferrimagnetic state accompanying a change in ME coefficient. To study the electronic structure of (Fe_1-xZn_x)₂Mo₃O₈, we carried out comprehensive measurements including Hard X-ray photoemission, soft x-ray absorption and resonant inelastic X-ray scattering. Our 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. We observed peculair temperature and polarization dependences of low-energy RIXS excitations across the phase transition of Fe₂Mo₃O₈.