Evaluation method for flux pinning properties in the mixed state of superconductors

超导体混合态磁通钉扎性能评价方法

基本信息

批准号：
18560309
负责人：
FUJIYOSHI Takanori
金额：
$ 2.37万
依托单位：
Kumamoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

1. As-grown MgB_2 thin films on Si substrates with high J_c under magnetic fields were prepared by electron-beam evaporation. The value of J_c has been enhanced by the deposition of MgB_2 thin film in an O_2 atmosphere. The MgB_2 thin film deposited in the O_2 atmosphere O_2-doped film has exhibited considerably higher J_c in magnetic fields among MgB_2 thin films reported before. It has been found that the high J_c of the O_2-doped film is attributable to the flux pinning with grain boundaries strengthened by an introduction of MgO along grain boundaries. In a high magnetic field, a peculiar behavior of E-J characteristics where E-J curves vary in two stages was observed. This behavior also originates from the flux pinning with strengthened grain boundaries.2. Flux pinning properties in ErBa_2Cu_3O_y and YBa_2Cu_3O_y thin films with BaZrO_3 nano-rods prepared by PLD were measured to investigate the flux pinning mechanism. The enhancement of J_c was confirmed by the measurement of the dependence of J_c on magnetic field. The angular dependence of J_c has a broad peak at B‖c-axis. This result indicates that the BaZrO_3 nano-rods work as the c-axis-correlated pinning centers. The pinning parameter m was evaluated from the electric fields versus current density characteristics and the peak of m appears in the magnetic field dependence. The characteristic behavior of m is caused by the matching of the density of BaZrO_3 nano-rods with that of fluxoids. It is found that the relative distribution width of the local critical current density for the ErBa2Cu_3O_y film with BaZrO_3 nano-rods is smaller than that of the YBa_2Cu_3O_y films with BaZrO_3 nano-rods.

1。通过电子梁蒸发制备具有高J_C的Si基板上的MGB_2薄膜。在O_2大气中，MGB_2薄膜的沉积增强了J_C的值。沉积在O_2大气中O_2掺杂膜中的MGB_2薄膜已在MGB_2薄膜中仔细地暴露了更高的J_C。已经发现，O_2掺杂膜的高J_C归因于通过沿晶界的MGO引入MGO增强的晶粒边界的通量固定。在高磁场中，观察到E-J特征的特殊行为在两个阶段观察到E-J曲线的变化。这种行为还源自磁通量，并以增强的晶界固定。2。测量了PLD制备的bazro_3纳米棒的ERBA_2CU_3O_Y和YBA_2CU_3O_Y薄膜中的通量固定属性，以研究通量固定机制。通过测量J_C对磁场的依赖性确认了J_C的增强。 J_C的角度依赖性在B轴时具有较大的峰值。该结果表明BAZRO_3纳米棒可作为C轴相关的固定中心。从电场与电流密度特性相比，评估了固定参数M，M的峰出现在磁场依赖性中。 M的特征行为是由Bazro_3纳米棒与棒流的密度匹配引起的。发现具有bazro_3纳米杆的ERBA2CU_3O_Y膜的局部临界电流密度的相对分布宽度小于带有bazro_3纳米棒的YBA_2CU_3O_Y膜的相对分布膜。