Growth of epitaxial high-entropy perovskite oxides by pulsed laser deposition

High entropy perovskite oxides (HEPO) have possible applications ranging from electromechanical, energy storage, and energy conversion devices. Although disordered, these chemically complex systems possess a large phase space to design and tune local properties such as charge and magnetism, which then modify macroscale properties that are critical electronic and optical properties, for example. Yet, understanding how to grow these materials as high-quality epitaxial thin films is critical to understanding their fundamental physical properties and ultimately utilizing the function phenomena for possible applications. In this talk we will discuss how the critical parameters for pulsed laser deposition affect the growth of several HEPOs. This includes structural aspects such as reflection high energy electron diffraction and X-ray diffraction studies, which are strongly affected by growth conditions such as oxygen pressure, temperature as well as laser fluence. We also will discuss how optimized growth parameters affect optical and electronic properties. Given the large phase space possible for HEPOs, we will discuss accelerating exploration of growth parameters through, for example, Gaussian process Bayesian optimization, which is a necessary future step to improve film quality and targeted improvement of key physical parameters.