Electron- and hole-doping effects on the electronic structure of manganite studied by X-ray absorption spectroscopy

摘要

The electronic structures of hole-doped La0.7Ca0.3MnO3 and electron-doped La0.7Ce0.3MnO3 manganites are investigated by x-ray absorption near-edge structure spectroscopy at the O and Mn K-, and Mn L-3,L-2-edges. The Mn K- and L-3,L-2-edge results show that Ce dopants increase the occupation of the Mn 4p and majority-spin e(g) orbitals and reduce the positive effective charge of some Mn ions. However, Ce doping also induces holes in O 2p derived states. As for La0.7Ca0.3MnO3, in contrast to previous understanding that Ca doping converts some Mn ions into the Mn4+ state, we find that Ca dopants actually increase the number of majority-spin e(g) electrons. We find instead that the holes created by Ca dopants are in the O 2p derived states.