We have studied the magnetization of vertically aligned graphene nanoflakes irradiated withnitrogen ions of 100 KeV energy and doses in the range 10^11–10^17 ions/cm^2. The non-irradiated graphene nanoflakes show a paramagnetic contribution, which is increased progressively by ion irradiation at low doses up to 10^15/cm^2. However, further increase on implantation dose reduces the magnetic moment which coincides with the onset of amorphization as verified by both Raman andx-ray photoelectron spectroscopic data. Overall, our results demonstrate the absence of ferromagnetism on either implanted or unimplanted samples from room temperature down to a temperature of 5 K.
Ney, A., Papakonstantinou, P., Ajay, K., Shang, NG., & Peng, N. (2011). Irradiation enhanced paramagnetism on graphene nanoflakes. Applied Physics Letters, 99, 102504-1. https://doi.org/10.1063/1.3628245