Weak ferromagnetism in thin fullerene films as a consequence of 600 keV carbon ion irradiation

We report weak ferromagnetism in fullerene thin films at the temperature of 2K-300K by 600 keV carbon ion irradiation. The fullerene thin films were irradiated with 600 keV carbon ions. The thin films of fullerene exhibit a significant and stable weak ferromagnetic ordering at room temperature after irradiation with variable ion fluence. Fullerene has exhibited a maximum magnetic ordering with carbon ion beam irradiation at the ion fluence of 0.03 pC/µm2 in the present experiment. The observed ferromagnetic ordering diminishes upon irradiation with higher fluences due to a higher degree of damage, which is confirmed by the Glancing angle x-ray diffraction and Raman analysis results. The saturation magnetic moments rapidly reduce, as we increase the fluence. Computational simulations have been performed to determine the approximate distance between defects and their relation with observed ferromagnetism, utilizing simulation studies from Stopping Range of Ions in Matter (SRIM) codes for the present experimental conditions. The correlation between theoretical as well as experimental studies reveals, that the fullerene thin films, get amorphized with the fluence of 0.03 pC/µm2 and beyond for 600 keV carbon ion irradiation. We have applied moderate ion flux to avoid the possibility of annealing during the carbon ion irradiation. We report our findings with systematic analysis in the present manuscript.