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Structural and chemical properties of superconducting Co-doped BaFe$_2$As$_2$ thin films grown on CaF$_2$

Grünewald, Lukas; Langer, Marco; Meyer, Sven; Nerz, Daniel; Hänisch, Jens; Holzapfel, Bernhard; Gerthsen, Dagmar

Abstract (englisch):
Thin films of Co-doped BaFe$_2$As$_2$ of similar thickness (~40 nm) were grown with different growth rates (0.4 Å s$^{-1}$ and 0.9 Å s$^{-1}$) by pulsed laser deposition on CaF$_2$(001) substrates. Analytical transmission electron microscopy (TEM) was applied to analyze the microstructure and secondary phases. The formation of BaF$_2$ and a high concentration of planar defects (mainly stacking faults) are observed for the sample grown at a low rate. A higher growth rate results in high-quality epitaxial films with only few antiphase boundaries. A higher $T_\text{c}$ was measured for the sample grown at a low growth rate, which is attributed to the difference in strain state induced by the high concentration of defects. Large crystalline Fe precipitates are observed in both samples. Chemical analysis shows a pronounced O and slight F content at the planar defects which highlights the role of O in defect formation. Electron-beam-induced irradiation damage during TEM measurements is observed and discussed.

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Originalveröffentlichung
DOI: 10.1088/1361-6668/abcecf
Zugehörige Institution(en) am KIT Institut für Technische Physik (ITEP)
Laboratorium für Elektronenmikroskopie (LEM)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 0953-2048, 1361-6668
KITopen-ID: 1000127053
HGF-Programm 37.06.02 (POF III, LK 01) New Power Network Technology
Erschienen in Superconductor science and technology
Verlag IOP Publishing
Vorab online veröffentlicht am 30.11.2020
Externe Relationen Supplement
Schlagwörter EELS, EDXS, STEM, Fe-based superconductor, Ba122, CaF2
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