Koblischka Michael R, Koblischka-Veneva Anjela, Schmauch Jörg, Murakami Masato
Experimental Physics, Saarland University, P.O. Box 151150, D-66044 Saarbrücken, Germany.
Superconducting Materials Laboratory, Department of Materials Science and Engineering, Shibaura Institute of Technology, Tokyo 135-8548, Japan.
Materials (Basel). 2019 Jul 6;12(13):2173. doi: 10.3390/ma12132173.
The flux pinning properties of reacted-and-pressed BaKFeAs powder were measured using magnetic hysteresis loops in the temperature range 20 K ≤ ≤ 35 K. The scaling analysis of the flux pinning forces ( F p = j c × B , with j c denoting the critical current density) following the Dew-Hughes model reveals a dominant flux pinning provided by normal-conducting point defects ( δ l -pinning) with only small irreversibility fields, H irr , ranging between 0.5 T (35 K) and 16 T (20 K). Kramer plots demonstrate a linear behavior above an applied field of 0.6 T. The samples were further characterized by electron backscatter diffraction (EBSD) analysis to elucidate the origin of the flux pinning. We compare our data with results of Weiss et al. (bulks) and Yao et al. (tapes), revealing that the dominant flux pinning in the samples for applications is provided mainly by grain boundary pinning, created by the densification procedures and the mechanical deformation applied.
使用磁滞回线在20 K≤T≤35 K的温度范围内测量了反应压制的BaKFeAs粉末的磁通钉扎特性。按照Dew-Hughes模型对磁通钉扎力（Fp = jc×B，其中jc表示临界电流密度）进行标度分析，结果表明，正常导电点缺陷（δl钉扎）提供了主要的磁通钉扎，不可逆磁场Hirr很小，范围在0.5 T（35 K）至16 T（20 K）之间。Kramer图表明，在0.6 T以上的外加磁场下呈现线性行为。通过电子背散射衍射（EBSD）分析对样品进行了进一步表征，以阐明磁通钉扎的起源。我们将我们的数据与Weiss等人（块体）和Yao等人（带材）的结果进行了比较，结果表明，用于应用的样品中的主要磁通钉扎主要由晶界钉扎提供，晶界钉扎是由致密化过程和施加的机械变形产生的。
