From Elements to Electronics: Designing Thin Film Perovskite Oxides for Technological Applications

Abstract

Oxide materials provide a wide range of functionalities for today's electronics, from battery cathodes to gate dielectrics. These applications take advantage of unique structural and electronic properties of oxide compounds. In this thesis, I use molecular beam epitaxy to synthesize atomically precise perovskite oxide thin films and characterize the resulting samples with techniques including electrical transport, x-ray diffraction and spectroscopy, and electron microscopy. I focus on the perovskite crystal structure $AB$O$_3$, a motif that demonstrates an incredibly diverse set of ground states among its members. Specifically, I explore three different perovskite families. I begin with the rare-earth nickelates, where I demonstrate the presence of an antiferromagnetic metal phase accessible via electron doping and further realize a strong antiferromagnetic memory behavior in the compound. Next I turn to a layered Ruddlesden-Popper chromate series where I demonstrate a transition from insulating to metallic behavior and use computational methods to understand the origin of this transition. Finally, I convert bismuthate perovskites to fluorite structures using topotactic fluorination and characterize the functionality of these fluorite compounds as electrolytes in fluoride-ion batteries.