Beyond Epitaxy: Ion Implantation as a Tool for Orbital Engineering

Area of Science:

• Materials Science
• Quantum Mechanics
• Solid-State Physics

Background:

• Electronic orbital states in quantum materials dictate their physical properties and functionality.
• Controlling these orbital states is crucial for developing advanced materials and devices.
• Existing methods, like heteroepitaxy, often fix orbital configurations during material synthesis.

Purpose of the Study:

• To demonstrate a novel postsynthesis method for tuning orbital populations in oxide thin films.
• To investigate the continuous and reversible control of orbital states using helium ion implantation.
• To explore the impact of orbital tuning on material properties and catalytic performance.

Main Methods:

• Utilized helium (He) ion implantation on lanthanum nickelate (LaNiO3) thin films.
• Systematically varied ion fluence to control the degree of orbital population shift.
• Analyzed changes in orbital occupation from in-plane (dx2-y2) to out-of-plane (dz2) states.

Main Results:

• Achieved continuous and reversible tuning of orbital populations in LaNiO3 thin films.
• Demonstrated a shift in orbital preference from dx2-y2 towards dz2 states with increasing He ion fluence.
• Showcased the ability to selectively modify specific regions of the film post-fabrication.

Conclusions:

• Helium ion implantation offers a versatile postsynthesis approach for orbital engineering in quantum materials.
• This strain-doping technique complements traditional synthesis methods and enables on-demand property modification.
• The demonstrated control over orbital states led to a significant enhancement in oxygen reduction reaction catalysis.