Directed Self-Assembly of Oxide Nanocomposites by Ion-Beam Lithography.

Su, Tingyu; Yu, Yang; Ross, Caroline A · Nano Lett · 2024

basic_science · Level V

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Abstract

Vertically aligned self-assembled nanocomposite films have provided a unique platform to study magnetoelectric effects and other forms of coupling between complex oxides. However, the distribution in the locations and sizes of the phase-separated nanostructures limits their utility. In this work, we demonstrate a process to template the locations of the self-assembled structure using ion lithography, which is effective for general insulating substrates. This process was used to produce a nanocomposite consisting of fin-shaped vertical nanostructures of ferroelectric BiFeO<sub>3</sub> and ferrimagnetic CoFe<sub>2</sub>O<sub>4</sub> with a feature size of 100 nm on (111)-oriented SrTiO<sub>3</sub> substrates. Cross-sectional imaging of the three-phase perovskite-spinel-substrate epitaxial interface reveals the selective nucleation of CoFe<sub>2</sub>O<sub>4</sub> in the trenches of the patterned substrate, and the magnetic domains of CoFe<sub>2</sub>O<sub>4</sub> were manipulated by applying an external magnetic field.