Electronic structure of YMn ₂O ₅ studied by EELS and first-principles calculations

The electronic structure of multiferroic YMn ₂O ₅ material has been studied by use of the generalized gradient approximation (GGA). The results demonstrate that the oxygen 2p and manganese 3d orbitals are strongly hybridized. Considering the on-site Coulomb interaction U, we performed the GGA+U calculations for 0 < U ≤ 8 eV, and it is found that the increase of U could enlarge the band gap and, on the other hand, weaken the Mn-O hybridization. The experimental measurements of the electron energy-loss spectrometry (EELS) exhibit a rich variety of structural features in both O-K edge and Mn-L edges. A theoretical and experimental analysis on the O-K edge suggests that the on-site Coulomb interaction (U) in YMn ₂ O ₅ could be less than 4 eV. Certain electronic structural features of LaMn ₂O ₅ have been discussed in comparison with those of YMn ₂O ₅.