Synthesis of High-Entropy Layered Oxide Epitaxial Thin Films: LiCr_1/6Mn_1/6Fe_1/6Co_1/6Ni_1/6Cu_1/6O₂

High-entropy oxides are emerging materials with unique functionalities. However, while various bulk-type high-entropy oxides have been developed, limited research has been pursued for high-entropy oxide thin films. In this paper, we report the synthesis of LiCr_1/6Mn_1/6Fe_1/6Co_1/6Ni_1/6Cu_1/6O₂ epitaxial thin films with a layered rocksalt structure via the pulsed laser deposition technique. We obtained a single-phase epitaxial thin film by tuning the laser fluence and substrate temperature. In addition, we fabricated a thin-film-type solid-state battery with the epitaxial thin film as a positive electrode. The battery exhibited stable operation. The results of this study provide a platform for synthesizing high-entropy oxide epitaxial thin films with the layered rocksalt structure.