Natural strong pinning in laser ablated YBa2Cu3O7-d thin films
Natural strong pinning in laser ablated YBa2Cu3O7-d thin films
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激光烧蚀 YBa2Cu3O7-d 薄膜中的自然强钉扎
DOI：
10.1103/physrevb.62.1338
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发表时间：
2000
影响因子：
3.7
通讯作者：
R. Griessen
中科院分区：
文献类型：
--
作者：
J. Huijbregtse;R. V. D. Geest;F. Klaassen;J. Rector;R. Elberse;B. Dam;R. Griessen
低温下，YBa2Cu3O7−δ薄膜的磁通钉扎中心主要是位错[B.Dam等，自然(伦敦)399,439(1999年)]。采用湿法化学腐蚀技术结合原子力显微镜，测量了激光烧蚀YBa2Cu3O7−δ薄膜的长度和横向位错分布。我们发现：(I)在薄膜生长的第一阶段，即靠近衬底-薄膜界面处，位错被诱导，并一直持续到平行于c轴的薄膜表面，导致均匀的长度分布；(Ii)径向位错分布函数表现出普遍的行为：它在小距离处接近于零，表明缺陷的短程有序化。这种生长诱导的相关无序的自组织使外延薄膜完全不同于通过重离子辐照产生的具有随机分布的柱状缺陷的单晶。由于衬底温度几乎可以在两个数量级(∼1-10 0/μm2)范围内调节位错密度ndisl，位错的诱导机制与YBa2Cu3O7−δ形核和生长机制密切相关。我们提出了在第一单分子层中优先析出和析出产生位错的证据。
At low temperatures dislocations are the dominant flux-pinning centers in thin films of YBa 2 Cu 3 O 7− δ deposited on (100) SrTiO 3 substrates [B. Dam et al., Nature (London) 399, 439 (1999)]. Using a wet-chemical etching technique in combination with atomic force microscopy, both the length and the lateral dislocation distribution are determined in laser ablated YBa 2 Cu 3 O 7− δ films. We find that (i) dislocations are induced in the first stages of film growth, ie, close to the substrate-film interface, and persist all the way up to the film surface parallel to the c axis, resulting in a uniform length distribution, and (ii) the radial dislocation distribution function exhibits a universal behavior: it approaches zero at small distances, indicating short-range ordering of the defects. This self-organization of the growth-induced correlated disorder makes epitaxial films completely different from single crystals with randomly distributed columnar defects created by means of heavy-ion irradiation. Since the substrate temperature can be used to tune the dislocation density n disl over almost two orders of magnitude (∼ 1–100/μ m 2), the mechanism by which dislocations are induced is closely related to the YBa 2 Cu 3 O 7− δ nucleation and growth mechanism. We present evidence for preferential precipitation in the first monolayer and precipitate generated dislocations.