Electron structure and magnetic properties of self-doped Pr 1-xMnO3+δ manganites: XANES and EXAFS study. Comparing with A- and B-site doped perovskites

Abstract

The local electronic and crystal structures of self-doped Pr1-xMnO3+δ (x = 0.0 and 0.2) perovskites are studied by x-ray absorption spectroscopy at Mn K-, Mn L- and O K-edges. The Mn K-edge shifts towards higher energy with increasing x indicating the increase in average manganese valence, which, in turn, leads to an increase in magnetization. The Mn L-edge spectra display a splitting into L3(2p3/2) and L2(2p1/2) peaks which is caused by core hole spin-orbit coupling. The intensities of 2p3/2 and 2p1/2 peaks increase with x, which correlates with the increase in magnetization and results from the change in hybridization between O 2p and Mn 3d orbitals. Altering x do not affect the O K-pre-edge spectra indicating no changes in Fermi level. Difference in relation of magnetic properties to electron structure in self-doped manganites and oxides doped in A- and B-positions of perovskites ABO3 cell is underlined. The Fourier transform of EXAFS spectra shows the decrease in oxygen and praseodymium contents and the formation of trivalent manganese anti-site defects in praseodymium position with increasing x.