Surface stoichiometry of La0.7Sr0.3MnO3 during in vacuo preparation; A synchrotron photoemission study |
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| Authors: | ÅF Monsen F Song ZS Li JE Boschker T Tybell E Wahlström JW Wells |
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| Institution: | 1. Department of Physics, Norwegian University of Science and Technology (NTNU), Trondheim, Norway;2. Zernike Institute of Advanced Materials, University of Groningen, 9747 AG, The Netherlands;3. Institute for the Storage Ring Facilities, University of Aarhus, Aarhus, Denmark;4. Department of Electronics and Telecommunications, Norwegian University of Science and Technology (NTNU), Trondheim, Norway;5. MAX-lab, Lund University, S-22100 Lund, Sweden |
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| Abstract: | We present a study of the surface stoichiometry and contamination of La0.7Sr0.3MnO3 thin films following exposure to air and subsequent in vacuo preparation. Samples were studied using both soft X-ray synchrotron photoemission (hν = 150 to 350 eV) and traditional Mg-Kα XPS (hν = 1253.6 eV) whilst annealing incrementally to ≈ 510°C in low pressures of O2. In all cases, a Mn depleted and Sr rich surface oxide layer is observed, it is of reduced crystalline quality and is charge depleted. This surface layer is weakly affected by subsequent annealing, and is partially reversed by annealing in higher O2 pressure. Surface carbon contamination is incrementally removed by annealing at increased temperatures, and at 270 °C, it is reduced to ≈ 0.4% of the topmost unit cell. The modification of the surface stoichiometry and electronic properties is consistent with the reported loss of magnetic properties in thin LSMO films. |
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