Electron microscope studies of nano-domain structures in Ru-based magneto-superconductors: RuSr₂Gd_1.5Ce_0.5Cu₂O_10−δ (Ru-1222) and RuSr₂GdCu₂O₈ (Ru-1212)

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• 作者：Tadahiro Yokosawa ; Veer Pal Singh Awana ; Koji Kimoto ; Eiji Takayama-Muromachi ; Maarit Karppinen ; Hisao Yamauchi ; Yoshio Matsui
• 刊名：Ultramicroscopy
• 出版年：2004
• 出版时间：January 2004
• 年：2004
• 卷：98
• 期：2-4
• 页码：283-295
• 全文大小：914 K

文摘

Microstructures of the RuSr₂Gd_1.5Ce_0.5Cu₂O_10−δ (Ru-1222) and RuSr₂GdCu₂O₈ (Ru-1212) magneto-superconductors have been investigated by using selected-area electron diffraction, convergent-beam electron diffraction, dark-field electron microscopy and high-resolution electron microscopy at room temperature. Both Ru-1212 and Ru-1222 consist of nm-size domains stacked along the c direction, where the domains are formed by two types of superstructures due to ordering of rotated RuO₆ octahedra about the c-axis. In Ru-1212, both primitive-and body-centered tetragonal superstructures (the possible space groups: P4/mbm and I4/mcm) are derived to form the corresponding nm-domains. It is of great interest that Ru-1212 consists of domains of two crystallographically different superstructures, while the similar domains observed in Ru-1222 have crystallographically identical superstructure with an orthorhombic symmetry (possible space group: Aeam), related by 90° rotation around the c-axis (Yokosawa et al., 2003, submitted for publication).