The synthesis of complex oxide thin films by the molecular-beam epitaxy (MBE) technique provides a great potential for unleashing novel and hidden properties of the material from the dull ground states. Especially, when it utilizes the lattice coherency from the substrates, i.e., strain, the properties of oxide thin films can be dramatically altered in comparison to their bulk form. Occasionally, this approach results in metastable phase and pseudomorphic polymorphism, thus, introducing the unexpected emergent properties owing to the power of epitaxial-strain-symmetry-stabilization at the interface. Therefore, the oxide thin-film approach for new quantum material discovery will be the ultimate platform for the fundamental study of new quantum phenomena at the surface and interface. 

  In this talk, I would like to present how ozone-assist oxide MBE can be useful to discover new material properties, especially, relevant to the strongly correlated electronic system. I will talk about (1) room temperature high-electron-mobility and its 2DEG behavior of the perovskite stannate interface for the transparent power electronics (2) how simple metal ruthenium dioxide becomes a superconductor via. strain-stabilization, and (3) realization of epitaxial topological crystalline insulator Sr₃SnO anti-perovskite system with in-situ spectroscopy. In addition to describing the above material synthesis and characterization, I also would like to discuss several challenging materials systems, for example, some cubic-to-hexagonal perovskite polymorphic systems, noble pyrochlore oxides system, and materials growth challenges containing alkaline metal elements (i.e., Li-, K-, Na- containing material system) for the fundamental study of quantum materials.