Pashitski AE, Gurevich A, Polyanskii AA, Larbalestier DC, Goyal A, Specht ED, Kroeger DM, DeLuca JA, Tkaczyk JE
A. E. Pashitski, A. Gurevich, A. A. Polyanskii, D. C. Larbalestier, Applied Superconductivity Center, University of Wisconsin, Madison, WI 53706, USA. A. Goyal, E. D. Specht, D. M. Kroeger, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA. J. A. DeLuca and J. E. Tkaczyk, General Electric, Schenectady, NY 12301, USA.
Science. 1997 Jan 17;275(5298):367-9. doi: 10.1126/science.275.5298.367.
Magneto-optical imaging was used to visualize the inhomogeneous penetration of magnetic flux into polycrystalline TlBa2Ca2Cu3Ox films with high critical current densities, to reconstruct the local two-dimensional supercurrent flow patterns and to correlate inhomogeneities in this flow with the local crystallographic misorientation. The films have almost perfect c-axis alignment and considerable local a- and b-axis texture because the grains tend to form colonies with only slightly misaligned a and b axes. Current flows freely over these low-angle grain boundaries but is strongly reduced at intermittent colony boundaries of high misorientation. The local (<10-micrometer scale) critical current density Jc varies widely, being up to 10 times as great as the transport Jc (scale of approximately 1 millimeter), which itself varies by a factor of about 5 in different sections of the film. The combined experiments show that the magnitude of the transport Jc is largely determined by a few high-angle boundaries.
利用磁光成像技术来可视化磁通量在具有高临界电流密度的多晶TlBa2Ca2Cu3Ox薄膜中的不均匀穿透情况，以重建局部二维超电流流动模式，并将这种流动中的不均匀性与局部晶体取向偏差相关联。这些薄膜具有几乎完美的c轴取向以及相当可观的局部a轴和b轴织构，因为晶粒倾向于形成a轴和b轴仅有轻微取向偏差的晶簇。电流可在这些低角度晶界上自由流动，但在高取向偏差的间歇性晶簇边界处会大幅降低。局部（<10微米尺度）临界电流密度Jc变化很大，高达传输Jc（约1毫米尺度）的10倍，而传输Jc本身在薄膜的不同部分也会有大约5倍的变化。综合实验表明，传输Jc的大小在很大程度上由一些高角度边界决定。
