XAS study of LaMn1−xGaxO3 series

Abstract

The LaMn1−xGaxO3 series has been studied by means of x-ray absorption spectroscopy (XAS) at the Mn and Ga K-edges. The local electronic and geometric structure around Ga3+ barely changes along the series showing that Ga3+ only acts as a constructive element of the crystal structure. On the contrary, the intensity of the pre-edge structures at the Mn K-edge shows a continuous decrease as the content of Ga increases. This result indicates a strong mixing of the 3-d states among near-neighbours Mn3+ ions. The local geometric structure around Mn3+ (MnO6 octahedron) also changes along the series. Namely, Mn3+ evolves from a cooperative static Jahn–Teller regime, as in LaMnO3, to a non-correlated dynamic Jahn–Teller regime (x > 0.5). Moreover, this result points to the lack of local tetragonal distortion for isolated Mn3+ ions.