Thursday, August 20, 2026
4:00 pm-5:00 pm
Epitaxy as a Platform for Fundamental Materials Discovery
Epitaxial thin-film growth provides a unique approach to exploring crystalline phases that are difficult or inaccessible to stabilize in their bulk form. By imposing structural constraints through a single-crystal substrate, epitaxy can modify lattice strain, symmetry, dimensionality, and interfacial structure, providing new pathways to control the structure–property relationship. In this sense, epitaxy is not only a method for synthesizing thin films, but also a platform for investigating how material structures and properties evolve under controlled non-equilibrium conditions.
In this talk, I will discuss how epitaxial growth techniques such as molecular-beam epitaxy (MBE) can be used to explore emergent phenomena in complex oxide systems. I will first highlight several examples in which epitaxial constraints lead to unusual electronic and structural states, including high-mobility two-dimensional electron systems in perovskite stannate heterostructures, strain-stabilized superconductivity in RuO₂, and the epitaxial realization of the topological crystalline insulator Sr₃SnO. These examples illustrate how controlling the growth environment and epitaxial constraints can provide access to material states beyond conventional bulk phases.
I will then discuss our recent efforts to extend this materials-by-design approach toward materials discovery in less-explored chemical spaces. Using suboxide MBE, we investigate the Sr–Ge–O system and find that the resulting film structures are strongly influenced by growth conditions and substrate symmetry. Epitaxial Sr–Ge–O films exhibit distinct growth modes and crystal structures depending on the Sr/GeO flux ratio, substrate temperature, and substrate choice, including phases not previously reported in existing databases. These observations suggest that epitaxial constraints can serve not only to stabilize known metastable phases, but also to uncover previously unexplored materials.
Together, these studies demonstrate how epitaxial growth can bridge materials synthesis and fundamental materials physics, providing a pathway to discover and understand new phases and emergent properties.
