Bulk electronic properties of the bilayered manganite La1.2Sr1.8Mn2O7 from hard-x-ray photoemission

We have performed hard-x-ray photoemission experiments at photon energy close to 6 keV on the ferromagnetic bilayered manganite La1.2Sr1.8Mn2O7 across its transition temperature T-C. Differences in both core level and valence band spectra have been observed as a function of temperature: We correlate the energy shift of the O 1s peak with a charge-transfer associated with the structural change taking place at the transition. A prominent shoulder on the low binding energy side of the Mn 2p core level that is observed below TC is tentatively ascribed to increased nonlocal screening in the ordered ferromagnetic phase.