Heat treatment and anomalous peak effect in Jc-H curve at 77 K for NdBa2Cu3O7-δ single-crystal superconductor

Masaru Nakamura, Yasuji Yamada, Tsukasa Hirayama, Yuichi Ikuhara, Yuh Shiohara, Shoji Tanaka

    研究成果: Article査読

    83 被引用数 (Scopus)

    抄録

    To investigate whether for NdBa2Cu3O7-δ (Nd 123) an anomalous peak effect in the magnetization hysteresis (M-H) loops at 77 K is an intrinsic property or not, different series of heat treatments were performed in a pure oxygen gas flow using Nd123 single crystal, and critical current density (JC)-H curves at 77 K were determined from the M-H loops. The JC-H curves with either H ∥ a-axis or H ∥ c-axis for a constant heat treatment at 340°C for 200 h showed no anomalous peak effect. On the other hand, when two step heat treatments, where the first step heat treatment was set to be at 500°C for 100 h and the second one was set to be at 340°C for 200 h, were carried out, the JC-H curve at 77 K with only H ∥ c-axis exhibited an anomalous peak effect. These results indicated that for Nd123 the anomalous peak effect in the JC-H curve at 77 K (in other words, the M-H loop) with H ∥ c-axis was considered to be not due to an intrinsic property. Further it was thought that the solid reaction occurred at 500°C and this solid reaction resulted in the formation of an anisotropic structure, causing an anomalous peak effect in the JC-H curve at 77 K with only H ∥ c-axis. Further the anomalous peak effect could be eliminated by the heat treatment. Therefore this solid reaction was found to be a reversible reaction. Accordingly the existence of the anomalous peak in the Jc-H curve at 77 K could be considered to be controlled by the heat treatment. We propose that the phase separation which is derived from the spinodal decomposition of an unstable solid solution takes place and the nano-scale microstructure resulting from phase separation leads to the anomalous peak effect and anisotropic property in the JC-H curve at 77 K.

    本文言語English
    ページ(範囲)295-303
    ページ数9
    ジャーナルPhysica C: Superconductivity and its applications
    259
    3-4
    DOI
    出版ステータスPublished - 1996 3月 15

    ASJC Scopus subject areas

    • 電子材料、光学材料、および磁性材料
    • 凝縮系物理学
    • エネルギー工学および電力技術
    • 電子工学および電気工学

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