Surface stoichiometry of La0.7Sr0.3MnO3 during in vacuo preparation; A synchrotron photoemission study

• 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 (hv = 150 to 350 eV) and traditional Mg-K alpha XPS (hv = 1253.6 eV) whilst annealing incrementally to approximate to 510 degrees C in low pressures of O-2. 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 O-2 pressure. Surface carbon contamination is incrementally removed by annealing at increased temperatures, and at 270 degrees C, it is reduced to approximate 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. (C) 2012 Elsevier B.V. All rights reserved.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Synchrotron photoemission

XPS

LSMO: oxide

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