Hard x-ray photoemission study of Mn 2p core-level on La1xSrxMnO3 thin films

Full text: In order to clarify the intrinsic bulk electronic structure of La1xSrxMnO3 (LSMO) thin films, we have performed high- energy (hv = 5.95 keV) synchrotron photoemission spectroscopy (PES) of Mn 2p core-level. In sharp contrast with previous soft x-ray PES (hv = 800 eV - 1486.6 eV), the high-energy PES spectra exhibit a clear additional peak at the low binding- energy side of the Mn 2p3/2 peak. To check for surface sensitivity, we measured take-off-angle dependence of Mn 2p core-levels. The results indicate that this additional peak originates from the bulk electronic structure. The peak shows a noticeable increase with decreasing temperature in the ferromagnetic metallic phase of LSMO x = 0.2 and x = 0.4, indicating that the origin of this peak is strongly related to the ferromagnetic and/or metallic physical properties of LSMO thin films. A single ion (MO6) cluster calculation cannot reproduce the new feature observed in Mn 2p core-levels, suggesting that the interaction between neighboring Mn atoms is important to reveal the intrinsic electronic structure of LSMO thin films