Local structure and electronic properties in colossally magnetoresistive thin film of La0.87Na0.13MnO3 by Mn-K edge EXAFS and XANES

Mn-K edge EXAFS and XANES spectra of La0.87Na0.13MnO3 manganite films with different thicknesses (750, 250, 125 and 50 Å), have been acquired at RT. In the 50 Å film a shift of the Fermi level downward in energy is found if compared to the other films. In addition, the density of the empty minority spin states is decreased. This finding has been attributed to the presence of some Mn ions experiencing a different local chemical environment that results in the breaking of some DE paths, and in addition to an Anderson localisation of the charge carriers. This last conclusion can explain both the strongly insulating nature and the spin glass like behaviour of the magnetic response of the 50 Å film, and has been corroborated by the results of the EXAFS analysis.