Pulsed-laser epitaxy of metallic delafossite PdCrO₂

Within the metallic ABO₂ delafossites, the natural heterostructuring among the A-layers, that are highly-conductive and 2-dimensional, with the triangular and localized nature on the BO₂ is a basic platform for many interesting phenomena. Thin film growth of these materials can enable both tuning basic properties as well as giving new insight into the novel phenomena found in this class of materials, yet this has proven extremely challenging. Here, we report the epitaxial growth of the metallic delafossite PdCrO₂ by pulsed laser deposition (PLD) across many different substrates and epitaxial buffer layers and growth conditions. This work has revealed the fundamental role PLD-growth conditions, epitaxial strain, and chemical and structural character of the substrate play in stabilizing the growth of PdCrO₂. It is found that a low-strain delafossite buffer layer is required to stabilize PdCrO₂. The resulting films are commensurately strained, show very narrow rocking curve widths as low as ~0.1°, and show an antiferromagnetic transition at 40 K that persists down to as thin as 3.6 nm. This works provides key insight for the growth of the boarder class of metallic delafossites and will enable tuning the basic properties of these interesting materials.