Mechanism of Oxygen Reduction via Chemical Affinity in NiO/SiO2 Interfaces Irradiated with keV Energy Hydrogen and Helium Ions for Heterostructure Fabrication

TL;DR

This study investigates how hydrogen and helium ion irradiation modify NiO/SiO2 interfaces, revealing hydrogen's chemical affinity with oxygen as key to reducing NiO to ferromagnetic Ni, enabling precise heterostructure fabrication.

Contribution

It demonstrates that hydrogen ion irradiation effectively reduces NiO to Ni via chemical affinity, providing a novel method for controlled heterostructure creation.

Findings

Hydrogen ions reduce NiO to Ni more efficiently than helium ions.

Hydrogen's chemical affinity with oxygen drives the reduction process.

Helium ions have negligible chemical affinity for oxygen, making them less effective.

Abstract

Low-energy light ion beams are an essential resource in lithography for nanopatterning magnetic materials and interfaces due to their ability to modify the structure and properties of metamaterials. Here we create ferromagnetic/non-ferromagnetic heterostructures with a controlled layer thickness and nanometer-scale precision. For this, hydrogen ion (H+) irradiation is used to reduce the antiferromagnetic nickel oxide (NiO) layer into ferromagnetic Ni with lower fluence than in the case of helium ion (He+) irradiation. Our results indicate that H+ chemical affinity with oxygen is the primary mechanism for efficient atom remotion, as opposed to He+ irradiation, where the chemical affinity for oxygen is negligible.