A comparison of the magnetic properties of radiation damaged or Co implanted ZnO single crystals

• Co implantation in ZnO single crystal introduces paramagnetic and ferromagnetic phases.
• Electron and proton irradiations have no effect on crystal magnetic properties.
• Co ions seem to stabilize the radiation defects.

To elucidate the interaction between defects and transition metal impurities in creating magnetic properties in wide band-gap semiconductors, single crystals of ZnO were irradiated with high-energy electrons, protons and Co ions. Magnetization of samples was measured before and after room temperature irradiation. The measurements reveal that only Co implantation creates measurable magnetization, which is related to the simultaneous introduction of defects. Consequences of the experimental results are discussed.