The atomic origins of reduced critical currents at [001] tilt grain boundaries in YBa2Cu3O7-δ thin films
The atomic origins of reduced critical currents at [001] tilt grain boundaries in YBa2Cu3O7-δ thin films
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DOI：
10.1016/s0921-4534(97)01689-4
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发表时间：
1998-01-10
期刊：
影响因子：
1.7
通讯作者：
Pennycook, SJ
中科院分区：
文献类型：
--
作者：
Browning, ND;Buban, JP;Pennycook, SJ
长期以来，人们已经知道晶界对高T-c氧化物超导体的输运性质具有有害的和不可再现的影响，特别是在高角度区域，其中已经报道了临界电流的指数下降。我们证明，通过结合原子分辨率Z-衬度成像和键价和分析，这是晶界的原子结构，占主导地位的这种行为。[001]YBa_2Cu_3O_（7-δ）薄膜中的倾斜晶界是由位错按一定顺序排列而成的，由此产生的应变场严重扰动了局域电子结构，导致晶界处出现非超导区。该区域的宽度随取向差角线性增加，自然地解释了所观察到的临界电流的指数下降。此外，对于给定的晶界取向差，变化很大的J（c）测量值可以自然地由晶界平面的小面化来解释。(C)1998年Elsevier Science B.V.
Grain boundaries have long been known to have a deleterious and irreproducible effect on the transport properties of high-T-c oxide superconductors, particularly in the high-angle regime where an exponential decrease in critical current has been reported. We demonstrate, through a combination of atomic resolution Z-contrast imaging and bond valence sum analysis, that it is the atomic structure of the grain boundary that dominates this behavior. [001] tilt grain boundaries in thin-film YBa2Cu3O7-delta are composed of arrays of dislocations in defined sequences, The resulting strain fields seriously perturb the local electronic structure, leading to a non-superconducting zone at the grain boundary. The width of this zone increases linearly with misorientation angle, naturally explaining the observed exponential decrease in critical current. In addition, the widely varying J(c) measurements for a given grain boundary misorientation can be naturally explained by the facetting of the grain boundary plane. (C) 1998 Elsevier Science B.V.