Scheid Anna, Heil Tobias, Suyolcu Y Eren, Song Qi, Enderlein Niklas, Nono Tchiomo Arnaud P, Ngabonziza Prosper, Hansmann Philipp, Schlom Darrell G, van Aken Peter A
Max Planck Institute for Solid State Research, Stuttgart 70569, Germany.
Department of Materials Sciences and Engineering, Cornell University, Ithaca, New York 14853, United States.
ACS Appl Mater Interfaces. 2025 Apr 23;17(16):24620-24629. doi: 10.1021/acsami.5c03536. Epub 2025 Apr 13.
Delafossites, composed of noble metal () and strongly correlated sublayers (O), form natural superlattices with highly anisotropic properties. These properties hold significant promise for various applications, but their exploitation hinges on the successful growth of high-quality thin films on suitable substrates. Unfortunately, the unique lattice geometry of delafossites presents a significant challenge to thin-film fabrication. Different delafossites grow differently, even when deposited on the same substrate, ranging from successful epitaxy to complete growth suppression. These variations often lack a clear correlation to obvious causes like lattice mismatch. Unidentified stabilization mechanisms appear to enable growth in certain cases, allowing these materials to form stable thin films or act as buffer layers for subsequent delafossite growth. This study employs advanced scanning transmission electron microscopy techniques to investigate the nucleation mechanism underlying the stable growth of PdCoO films on AlO and LaAlO substrates grown via molecular-beam epitaxy. Our findings reveal the presence of a secondary phase within the substrate surface that stabilizes the films. This mechanism deviates from the conventional understanding of strain relief mechanisms at oxide heterostructure interfaces and differs significantly from those observed for Cu-based delafossites.
由贵金属（）和强关联亚层（O）组成的铜铁矿形成具有高度各向异性性质的天然超晶格。这些性质在各种应用中具有重大潜力，但其开发取决于在合适衬底上成功生长高质量薄膜。不幸的是，铜铁矿独特的晶格几何结构给薄膜制造带来了重大挑战。即使沉积在同一衬底上，不同的铜铁矿生长方式也不同，从成功外延生长到完全抑制生长。这些变化通常与晶格失配等明显原因缺乏明确关联。在某些情况下，不明的稳定机制似乎能促进生长，使这些材料形成稳定的薄膜或作为后续铜铁矿生长的缓冲层。本研究采用先进的扫描透射电子显微镜技术，研究通过分子束外延在AlO和LaAlO衬底上生长的PdCoO薄膜稳定生长的成核机制。我们的研究结果揭示了衬底表面存在一个稳定薄膜的第二相。这种机制不同于对氧化物异质结构界面应变缓解机制的传统理解，且与基于铜的铜铁矿所观察到的机制有显著差异。
