Colloquium with Dr. Ryan Comes, Thomas and Jean Walter Assistant Professor of Physics, Auburn University

Interfacial Band Engineering of Oxide Heterostructures for Electronic, Energy, and Quantum Systems

Complex oxides comprised of multiple positively charged metal cations exhibit a host of intriguing and useful properties for new technologies. Perovskite oxides with the chemical formula ABO3 have some of the richest behavior. These materials may be metallic, semiconducting, or insulating, and exhibit ferroelectricity, ferromagnetism, or superconductivity. This combination of properties in a single class of materials offers rich opportunities for engineering of unusual combinations of behavior through the design of multi-layer thin film materials. Using molecular beam epitaxy (MBE), we are able to engineer these materials down to the atomic level so that interfaces between two different materials can be controlled to produce desirable properties for electronic, energy, and quantum applications. In this talk I will show how we can optimize electronic properties using in situ techniques to understand the film growth process and resulting electronic properties. In the first part of the talk, I will introduce how we have employed MBE and in situ X-ray photoelectron spectroscopy (XPS) plus density functional theory to understand the catalytic performance of LaFeO3 and LaNiO3 heterostructures for the oxygen evolution reaction. Later, I will also show how hybrid MBE can enable synthesis of hard to grow materials using metalorganic precursors, including SrNbO3, SrTaO3, and SrHfO3. Ongoing work focuses on the use of these materials to produce novel oxide heterostructures for topological phases, high electron mobility 2D electron gases, and spintronic devices.