The valence state of Ce in electron-doped manganites: La0.7Ce0.3MnO3

The electronic structure of La0.7Ce0.3MnO3 (LCeMO) has been investigated by using photoemission spectroscopy. A very weak 4f resonance is observed and the Ce 3d spectrum of LCeMO is very similar to that of CeO2, indicating that Ce ions are far from being trivalent. The Mn 2p core-level spectrum of LCeMO is essentially the same as that of hole-doped La0.7Sr0.3MnO3, but different from that of MnO. The local spin-density approximation (LSDA) electronic structure calculations for LCeMO show that the Mn 3d states contribute a large peak around -2 eV and a weak structure between -2 eV and EF, and that the O 2p states are spread between -3 eV and -9 eV, with negligible contribution near EF. The LSDA calculations for LCeMO and hole-doped La0.7Ba0.3MnO3 reveal that the calculated Mn 3d density of states at EF in LCeMO is larger, reflecting the effect of electron doping with Ce ions.