Flux pinning landscape up to 25 T in SmBa2Cu3O y films with BaHfO3 nanorods fabricated by low-temperature growth technique
Flux pinning landscape up to 25 T in SmBa2Cu3O y films with BaHfO3 nanorods fabricated by low-temperature growth technique
复制标题
采用低温生长技术制造的 BaHfO3 纳米棒的 SmBa2Cu3O y 薄膜中的通量钉扎景观高达 25 T
DOI：
10.1088/1361-6668/aa7ef0
复制
发表时间：
2017
影响因子：
3.6
通讯作者：
Yoshida Yutaka
中科院分区：
文献类型：
--
作者：
Tsuchiya Yuji;Miura Shun;Awaji Satoshi;Ichino Yusuke;Matsumoto Kaname;Izumi Teruo;Watanabe Kazuo;Yoshida Yutaka
REBa 2 Cu 3 O y 超导带适合低温（即低于液氮温度）下的高场磁体应用。为了阐明低温下有效钉扎中心的形貌和体积，我们采用低温生长技术在离子束辅助沉积的MgO缓冲金属基底上制备了含有不同数量的BaHfO 3 (BHO)纳米棒的SmBa 2 Cu 3 O y (SmBCO)薄膜；我们使用东北大学最近开发的 25 T 无冷冻剂超导磁体研究了它们的通量钉扎特性。根据透射电子显微镜的微观结构分析，BHO 纳米棒具有含量依赖性形态，并针对较高含量排列。 BHO含量高达3.8 vol%的SmBCO薄膜中观察到倾斜且不连续的BHO纳米棒；即使磁场垂直于薄膜，它们也表现出优异的磁通钉扎力密度（21 T 和 4.2 K 时为 1.5 TN m− 3）。根据磁通钉扎的有效质量模型，随机钉扎中心在低温下占主导地位。对于对齐的纳米棒，相关通量钉扎更强；然而，在 4.5 vol% BHO 掺杂薄膜中，随机钉扎中心变得较弱。因此，就临界电流密度幅度和 4.2 K 至 20 K 的各向异性而言，最佳 BHO 掺杂水平约为 3.8 vol%，因为这提供了相关和随机通量钉扎中心的最佳混合。
REBa 2 Cu 3 O y superconducting tapes are appropriate for high field magnet applications at low temperatures (ie below liquid nitrogen temperature). To clarify the morphology and the volume of the effective pinning center at low temperatures, we used a low-temperature growth technique to fabricate SmBa 2 Cu 3 O y (SmBCO) films with various amounts of BaHfO 3 (BHO) nanorods onto MgO-buffered metal substrates produced by ion-beam-assisted deposition; we investigated their flux pinning properties using a 25 T cryogen-free superconducting magnet that was recently developed at Tohoku University. According to the microstructural analysis using transmission electron microscopy, the BHO nanorods have a content-dependent morphology and are aligned for the higher content. The inclined and discontinuous BHO nanorods were observed in SmBCO films with BHO contents up to 3.8 vol%; they show an excellent flux pinning force density (1.5 TN m− 3 at 21 T and 4.2 K) even when the magnetic field is perpendicular to the films. Based on the effective mass model for the flux pinning, the random pinning centers are dominant at low temperatures. The correlated flux pinning is stronger for aligned nanorods; however, the random pinning center becomes weaker in the 4.5 vol% BHO-doped films. Therefore, the optimal BHO doping level is approximately 3.8 vol% in terms of the amplitude of the critical current density and the anisotropy from 4.2 K to 20 K because this provides the best mixture of correlated and random flux pinning centers.