In situ characterization of strontium surface segregation in epitaxial La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films as a function of oxygen partial pressure.
Using in situ synchrotron measurements of total reflection x-ray fluorescence, we find evidence of strontium surface segregation in (001)-oriented La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films over a wide range of temperatures (25-900 C) and oxygen partial pressures (pO{sub 2} = 0.15-150 Torr). The strontium surface concentration is observed to increase with decreasing pO{sub 2}, suggesting that the surface oxygen vacancy concentration plays a significant role in controlling the degree of segregation. Interestingly, the enthalpy of segregation becomes less exothermic with increasing pO{sub 2}, varying from -9.5 to -2.0 kJ/mol. In contrast, the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} film thickness and epitaxial strain state have little impact on segregation behavior.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 985116
- Report Number(s):
- ANL/MSD/JA-62185; TRN: US1006077
- Journal Information:
- Appl. Phys. Lett., Vol. 93, Issue 2008
- Country of Publication:
- United States
- Language:
- ENGLISH
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