  We have studied the magnetization of vertically aligned graphene nanoflakes
irradiated with nitrogen ions of 100 KeV energy and doses in the range 10^11-
10^17 ions/cm2. 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 and X-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 5K
