Magnetic Field Dependence of Critical Current Density of PLD RE-Ba-Cu-O (RE=Gd, Sm, Dy, Er, Y) Film on CeO 2 Capped IBAD
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Magnetic Field Dependence of Critical Current Density of PLD RE-Ba-Cu-O (RE=Gd, Sm, Dy, Er, Y) Film on CeO2 Capped IBAD-GZO Layers Kazuhiro Takahashi1, Masaya Konishi1, Akira Ibi1, Tomonori Watanabe1, Takemi Muroga1, Seiki Miyata1, Yutaka Yamada1, Yuh Shiohara2, Takeharu Kato3 and Tsukasa Hirayama3 1 Superconductivity Research Laboratory, ISTEC, 2-4-1 Mutsuno, Atsuta-ku, Nagoya, 456-8587, Japan 2 Superconductivity Research Laboratory, ISTEC, 1-10-13 Shinonome, Koto-ku, Tokyo 135-0062, Japan 3 Materials R&D Laboratory, Japan Fine Ceramics Center, 2-4-1 Mutsuno, Atsuta-ku, Nagoya 456-8587, Japan ABSTRACT We prepared REBa2Cu3O7- δ (RE= Gd, Sm, Dy, Er, Y) coated conductors on pulsed laser deposition (PLD) -CeO2/ion-beam assisted deposition (IBAD) – Gd2Zr2O7 (GZO) / metal tapes by the PLD method and measured the characteristics in magnetic fields. The GdBa2Cu3O7- δ (Gd-123) films showed superior characteristics than others in magnetic fields and showed weak anisotropy. Critical current density (Jc) value of the Gd-123 film was 3.87MA/ cm2 at self-field and 0.19MA/cm2 at 3 T of perpendicular field to the tape surface in liquid nitrogen (77 K). Angular dependences in magnetic fields (Jc -θ) of the Gd-123 and the SmBa2Cu3O7- δ (Sm-123) were superior to others and peaks in Jc -θ were found also at 0 degree. The reduction ratios of Jc in Jc -θ for the Gd-123 film and the Sm-123 film were smaller than other films. Transmission electron microscopy showed that the Gd-123 film had many stacking faults. It may be considered that this stacking faults naturally introduced by the PLD method contribute to improvement of anisotropy of Jc -θ in the Gd-123 film. INTRODUCTION For a practical application of high-critical temperature (Tc) superconductors, high critical current density (Jc) and critical current (Ic) in high magnetic fields at high temperature are required. Recently coated conductor using YBa2Cu3O7- δ (Y-123) films has been intensively studied and various attempts have been tried to improve Jc and Ic. One of such candidates is a self-epitaxy method, in which CeO2 layer is formed by the pulsed laser deposition (PLD) on an ion-beam assisted deposition (IBAD) – Gd2Zr2O7 (GZO) layer and improves the in-plane alignment [1]. Using this substrate, high Jc was obtained for continuously deposited Y-123 films with a reel-to-reel process as well as those in short batch type samples [2, 7]. On the other hand, some REBa2Cu3O7- δ (or RE-123,RE=rare earth) superconductor films, in which yttrium in Y-123 is substituted by rare earth element, is reported to show superior characteristics such as Tc and critical magnetic field. Then, less degradation of Jc for the RE-123 will be expected in a magnetic field than that for the Y-123 films [3-6]. From this point, we fabricated the RE-123 (RE=Gd, Sm, Dy, Er, Y) films with various thickness on the PLD-CeO2/IBAD-GZO layers and investigated Jc properties in magnetic field up to 8 T.
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EXPERIMENTAL DETAILS RE-123 films with thicknesses of 0.25 to 2.0 µm were deposited by the PLD metho
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