ABSTRACT We previously reported that out-of-plane lattice of in-plane tensile strained (001) La0.7Ca0.3MnO3 thin films can be stretched by He treatment of the films via adding helium gas in an Ar/O2 mixed sputtering atmosphere. To gain more insight into the He treatment process, in this study, we carried out He plasma treatment on a target and He atom adsorption on a substrate surface respectively before/between sputtering deposition of La0.7Ca0.3MnO3 films. The films deposited after the target pre-treatment show remarkable changes in the out-of-plane lattice and magnetotransport properties, while the films deposited through the latter method changes only slightly, suggesting that the He+ ion penetration in the cathode target plays a key role in the He treatment of the manganite films. Furthermore, we placed the as-grown films at the cathode position and exposed them directly to He discharge plasma. After the He plasma post-treatment, the out-of-plane lattice parameter increases from 3.823 to 3.851A, accompanied by an increase in the metal-insulator transition temperature from 260 to 290 K. The results demonstrate that the He plasma treatment is a simple strategy for the single-axis control of epitaxial thin films.

中文翻译：

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溅射阴极材料中的氦离子渗透：氧化物薄膜氦处理的关键过程

摘要 我们之前报道过面内拉伸应变 (001) La0.7Ca0.3MnO3 薄膜的面外晶格可以通过在 Ar/O2 混合溅射气氛中添加氦气对薄膜进行 He 处理来拉伸。为了更深入地了解 He 处理过程，在本研究中，我们分别在溅射沉积 La0.7Ca0.3MnO3 薄膜之前/之间对靶材进行了 He 等离子体处理，并在基板表面进行了 He 原子吸附。靶材预处理后沉积的薄膜在面外晶格和磁传输性能方面表现出显着变化，而通过后一种方法沉积的薄膜仅略有变化，表明阴极靶材中的 He+ 离子渗透起着关键作用在锰膜的 He 处理中。此外，我们将生长的薄膜放在阴极位置，并将它们直接暴露在 He 放电等离子体中。He等离子体后处理后，面外晶格参数从3.823增加到3.851A，伴随着金属-绝缘体转变温度从260增加到290 K。结果表明He等离子体处理是外延薄膜单轴控制的简单策略。