Layer-by-layer epitaxial growth of monoclinic SrIrO3 thin films on (111)-oriented SrTiO3 through interface engineering

Abstract

When transition metal oxides is grown along (111) direction, a variety of intriguing phenomena is expected to arise. One of important system, SrIrO3, crystallizes into monoclinic hexagonal-based 6M structure when grown on (111)-oriented perovskite SrTiO3, and is expected to host novel topological states. However, the growth of high quality SrIrO3 on (111)-oriented substrate is still a challenge. We report on high-quality layer-by-layer epitaxial growth of monoclinic SrIrO3 on SrTiO3(111) substrate by inserting the CaTiO3 buffer layer. The scanning transmission electron microscopy image shows perfect epitaxial growth of monoclinic SrIrO3. Reflection high-energy electron diffraction and low-energy electron diffraction patterns exhibit smooth film surface with reconstruction. Inserting CaTiO3 buffer layer proves to be an effective way of interface engineering in realizing layer-by-layer growth by reducing the lattice mismatch. The study paves way for the future research on novel quantum states in monoclinic SrIrO3 films and heterostructures.