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 deg. C) and oxygen partial pressures (pO{sub 2}=0.15-150 Torr). The...

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Bibliographic Details
Published in:Applied physics letters 2008-10, Vol.93 (15)
Main Authors: Fister, Tim T., Fong, Dillon D., Eastman, Jeffrey A., Baldo, Peter M., Highland, Matthew J., Fuoss, Paul H., Balasubramaniam, Kavaipatti R., Meador, Joanna C., Salvador, Paul A.
Format: Article
Language:English
Subjects:
CRYSTAL GROWTH
CRYSTALS
ENTHALPY
EPITAXY
FLUORESCENCE
LANTHANUM COMPOUNDS
LAYERS
MANGANATES
MATERIALS SCIENCE
OXYGEN
PARTIAL PRESSURE
SEGREGATION
STRONTIUM
STRONTIUM COMPOUNDS
SURFACE PROPERTIES
SYNCHROTRONS
THIN FILMS
VACANCIES
X-RAY FLUORESCENCE ANALYSIS
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Summary: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 deg. 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.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.2987731