AIテープ基板上に作製した無添加MgB2薄膜の輸送特性

概要

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An MgB2 superconductor has the highest Tc among metallic superconductors. However, high Jc MgB2 wires are not currently obtained by major methods such as the power in tube method. Therefore, we prepared MgB2 thin films on Al tape substrates by EBE to fabricate high Jc MgB2 wires. The MgB2 thin films on Al tape substrates showed high Jc in Low magnetic fields for B//c. However, the Jc of the MgB2 thin film on Al tape substrate is suppressed drastically in high magnetic fields. In the field angular dependence of Jc, the peak appears at B//c due to c-axis correlated pinning centers. The magnetic field dependence of the reduced macroscopic pinning force density indicates that the additional pinning centers besides the grain boundary are found in the MgB2 thin films. These pinning centers are caused by the magnesium deficiency or the substitution of boron for magnesium site.
2011-03-00