Crystalline Ni nanoparticles as the origin of ferromagnetism in Ni implanted ZnO crystals

TL;DR

This study demonstrates that ferromagnetism in Ni-implanted ZnO crystals primarily originates from crystalline Ni nanoparticles formed during implantation, rather than from a diluted magnetic semiconductor.

Contribution

It provides evidence that crystalline Ni nanoparticles are the main source of ferromagnetism in Ni-implanted ZnO, clarifying the magnetic origin in such systems.

Findings

Crystalline Ni nanoparticles are formed inside ZnO during implantation.

Magnetic properties are mainly due to Ni nanoparticles, not diluted magnetic semiconductor effects.

Magnetization behavior aligns with a Ni nanoparticle system.

Abstract

We report the structural and magnetic properties of ZnO single crystals implanted at 623 K with up to 10 at. % of Ni. As revealed by X-ray diffraction, crystalline fcc-Ni nanoparticles were formed inside ZnO. The magnetic behavior (magnetization with field reversal and with different temperature protocol) of all samples is well explained by a magnetic Ni-nanoparticle system. Although the formation of Ni:ZnO based diluted magnetic semiconductor cannot be ruled out, the major contribution to the magnetic properties stems from crystalline nanoparticles synthesized under these implantation conditions.