Epitaxial thin films of pyrochlore iridates: A forward looking approach

Topological quantum materials that show strongly correlated electrons as well as topological order, for which spin–orbit coupling is a key ingredient, exhibit novel states of matter. One such example is the family of pyrochlore iridates, featuring strong spin–orbital coupling, strong electron interactions, as well as geometric frustration, making them an ideal platform to study novel topological phases. High-quality epitaxial pyrochlore iridate films, although challenging to produce, provide a pathway to explore unconventional behaviors and unravel the intrinsic properties of these largely unexplored materials. Additionally, designing interfaces with specific properties is crucial to creating multilayered devices that can achieve significant technological breakthroughs using topological states of these materials. This article reviews experimental research on epitaxial pyrochlore iridate thin films, discussing evidence of topological phases found in them. Future research directions are outlined, which include exploring the rich tunability offered by chemical doping, especially when combined with the design of epitaxial heterostructures.