The oxides of platinum group metals are promising for future electronics and spintronics due to the delicate interplay of spin-orbit coupling and electron correlation energies. However, their synthesis as thin films remains challenging due to their low vapour pressures and low oxidation potentials. Here we show how epitaxial strain can be used as a control knob to enhance metal oxidation. Using Ir as an example, we demonstrate the use of epitaxial strain in engineering its oxidation chemistry, enabling phase-pure Ir or IrO₂ films despite using identical growth conditions. The observations are explained using a density-functional-theory-based modified formation enthalpy framework, which highlights the important role of metal-substrate epitaxial strain in governing the oxide formation enthalpy. We also validate the generality of this principle by demonstrating epitaxial strain effect on Ru oxidation. The IrO₂ films studied in our work further revealed quantum oscillations, attesting to the excellent film quality. The epitaxial strain approach we present could enable growth of oxide films of hard-to-oxidize elements using strain engineering.

由于自旋轨道耦合和电子关联能之间微妙的相互作用，铂族金属的氧化物在未来的电子学和自旋电子学中具有广阔的前景。然而，由于其低蒸气压和低氧化电位，将它们合成为薄膜仍然具有挑战性。在这里，我们展示了如何使用外延应变作为控制旋钮来增强金属氧化。以 Ir 为例，我们展示了在设计其氧化化学过程中使用外延应变，尽管使用相同的生长条件，仍可实现相纯 Ir 或 IrO ₂薄膜。使用基于密度泛函理论的修正形成焓框架来解释观察结果，该框架强调了金属基底外延应变在控制氧化物形成焓中的重要作用。我们还通过证明外延应变对 Ru 氧化的影响来验证该原理的普遍性。我们工作中研究的IrO ₂薄膜进一步揭示了量子振荡，证明了优异的薄膜质量。我们提出的外延应变方法可以利用应变工程来生长难氧化元素的氧化膜。