In vacuo photoemission study of atomically controlled La1-xSrxMnO3 thin films:: Composition dependence of the electronic structure -: art. no. 155420

We have investigated change in the electronic structures of atomically controlled La1-xSrxMnO3 (LSMO) thin films as a function of hole-doping levels (x) in terms of in vacuo photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS) measurements. The in vacuo PES measurements on a well-ordered surface of high-quality epitaxial LSMO thin films enable us to reveal their intrinsic electronic structures, especially the structure near the Fermi level (E-F). We found that overall the features of the valence band as well as the core levels monotonically shifted toward lower binding energy as x was increased, indicating the systematic chemical-potential shift of LSMO thin films with hole doping. The peak nearest to E-F due to the e(g) orbital is also found to move toward E-F, while the peak intensity decreases with increasing x. The loss of spectral weight with x in the occupied density of states was compensated by the simultaneous increment of the shoulder structure in O 1s XAS spectra, suggesting the existence of a pseudogap, that is, a lowering in spectral weight at E-F, for all metallic compositions. These results indicate that the simple rigid-band model does not describe the electronic structure near E-F of LSMO, and that the spectral weight transfer from below to above E-F across the gap dominates the spectral changes with x in LSMO thin films.