Controlling phase transitions in transition metal oxides remains a central feature of both technological and fundamental scientific relevance. A well-known example is the metal–insulator transition, which has been shown to be highly controllable. However, the length scale over which these phases can be established is not yet well understood. To gain insight into this issue, we atomically engineered an artificially phase-separated system through fabricating epitaxial superlattices that consist of SmNiO₃ and NdNiO₃, two materials that undergo a metal-to-insulator transition at different temperatures. We demonstrate that the length scale of the interfacial coupling between metal and insulator phases is determined by balancing the energy cost of the boundary between a metal and an insulator and the bulk phase energies. Notably, we show that the length scale of this effect exceeds that of the physical coupling of structural motifs, which introduces a new framework for interface-engineering properties at temperatures against the bulk energetics.

控制过渡金属氧化物中的相变仍然是技术和基础科学相关性的主要特征。一个著名的例子是金属-绝缘体的转变，它已被证明是高度可控的。但是，尚不能很好地理解这些阶段可以建立的长度尺度。为了深入了解此问题，我们通过制造由SmNiO ₃和NdNiO ₃组成的外延超晶格，对原子相分离系统进行了原子工程设计。，两种材料会在不同的温度下经历金属到绝缘体的转变。我们证明，金属和绝缘体相之间的界面耦合的长度尺度是通过平衡金属和绝缘体之间的边界的能量成本与体相能量来确定的。值得注意的是，我们表明，这种效应的长度尺度超过了结构图案的物理耦合，从而引入了一个新的框架，用于在高温下抵抗本体能的界面工程特性。