Microstructure and transport properties of [0 0 1]-tilt bicrystal grain boundaries in iron pnictide superconductor, cobalt-doped BaFe₂As₂

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• 作者：Hidenori Hiramatsu^a ; ^{h-hirama@lucid.msl.titech.ac.jp} ; Takayoshi Katase^a ; Yoshihiro Ishimaru^b ; Akira Tsukamoto^b ; Toshio Kamiya^a ; Keiichi Tanabe^b ; Hideo Hosono^a ; ^c
• 关键词：Pnictide ; Thin film ; Bicrystal ; Grain boundary ; Critical current density
• 刊名：Materials Science and Engineering ; B
• 出版年：2012
• 期刊代码：76_09215107
• 类别：ch
• 出版时间：25 April, 2012
• 卷：177
• 期：7
• 页码：515-519
• 文件大小：1203 K

摘要

Relationships between microstructure and transport properties of bicrystal grain boundary (BGB) junctions were studied in cobalt-doped BaFe₂As₂ (BaFe₂As₂:Co) epitaxial films grown on [0 0 1]-tilt bicrystal substrates of MgO and (La, Sr)(Al, Ta)O₃ with misorientation angles 胃_GB = 3-45掳. The 胃_GB of BaFe₂As₂:Co BGBs were exactly transferred from those of the bicrystal substrates. No segregation of impurities was detected at the BGB junction interfaces, and the chemical compositions of the BGBs were uniform and the same as those in the bulk film regions. A transition from a strongly-coupled GB behavior to a weak-link behavior was observed in current density-voltage characteristics under self-field around 胃_GB 鈭?#xA0;9掳. The critical current density decreased from (1.2-1.6) 脳 10⁶ A/cm² of the intragrain transport to (0.7-1.1) 脳 10⁵ A/cm² of 胃_GB = 45掳 because supercurrent becomes more governed by Josephson current with increasing 胃_GB.