Critical state model determined from flux-creep activation energy in SmBa<sub>2sub>Cu<sub>3sub>O<sub>ysub> superconductor

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• 作者：Lee ; J.H. ; Kim ; G.C. ; Kim ; Y.C. ; Jeong ; D.Y.
• 关键词：74.72 ; Activation energy ; Magnetic relaxation ; Critical state model ; SmBa<sub>2sub>Cu<sub>3sub>O<sub>ysub>
• 刊名：Physica C: Superconductivity and its applications
• 出版年：2005
• 出版时间：February 1, 2005
• 年：2005
• 卷：418
• 期：3-4
• 页码：131-137
• 全文大小：699 K

文摘

Time dependent magnetization was measured on two forms (polycrystal and aligned grains) of high-T<sub>csub> superconductor SmBa<sub>2sub>Cu<sub>3sub>O<sub>ysub>. The flux-creep activation energy obtained in the aligned grains showed inverse dependence on current density as expected from collective flux-creep theory. However, that obtained from a polycrystal, which can be called intergranular flux-creep activation energy, showed linear dependence on current density as suggested by Kim-Anderson model. This proves that Kimaaas critical state model is more suitable to the intergranular system, where flux lines should be in fixed positions and have fixed sizes, than the flux bundle system. In the critical state, where the pinning force is balanced with Lorentz force, the collective pinning theory is proved to be related to the generalized critical state model, which needs to be modified by surface-barrier effect when it is applied to MaaaH curve fitting of aligned grains.