The emergent phenomena in complex oxide thin films are strongly tied to the oxygen content, which is often engineered by the oxygen partial pressure during growth. However, such oxygen control by the growth pressure is challenging to synthesize for some oxide films, which requires a subtle control of the oxygen content. A parameter of controlling the oxygen content independent of the growth pressure is desired. Here, we propose a method of controlling the oxygen content of films by engineering the substrate before the growth. The oxide substrate serves as an oxygen sponge, which provides a tunable oxygen environment ranging from oxygen-rich to oxygen-poor for the film growth, depending on the pre-substrate annealing (PSA) conditions. Using manganite as a model system, we demonstrate that this simple PSA method leads to remarkable changes in the structure and physical properties of the as-grown films. This substrate oxygen sponge effect, driven by the large oxygen concentration gradient at high temperatures, can be applied to explore not only emergent interfacial phenomena but also the growth of a variety of functional oxide thin films and nanocomposites.

中文翻译：

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衬底吸氧效应：外延锰矿薄膜生长的参数

复杂氧化物薄膜中出现的现象与氧含量密切相关，而氧含量通常是由生长过程中的氧分压设计的。然而，这种通过生长压力控制氧对于某些氧化膜的合成具有挑战性，这需要对氧含量进行微妙的控制。需要独立于生长压力来控制氧含量的参数。在这里，我们提出了一种通过在生长前设计基板来控制薄膜氧含量的方法。氧化物基板充当氧海绵，根据基板前退火 (PSA) 条件，为薄膜生长提供从富氧到缺氧的可调氧环境。使用锰矿作为模型系统，我们证明了这种简单的 PSA 方法会导致生长薄膜的结构和物理性能发生显着变化。这种由高温下大氧浓度梯度驱动的基材吸氧效应不仅可用于探索出现的界面现象，还可用于探索各种功能性氧化物薄膜和纳米复合材料的生长。