This comment addresses several issues in the paper by Sepioni et al., where it is stated that the ferromagnetism in pristine highly oriented pyrolytic graphite (HOPG) reported by several groups in the previous years is most likely due to impurity con
tamination. In this comment, clear arguments are given why this statement is not justified. Furthermore, it is pointed out, that there are already measurements using element-sensitive microscopic techniques, e.g. X-ray Magnetic Circular Dichroism (XMCD) that directly proved the intrinsic origin of the ferromagnetism in graphite, also in pristine HOPG.
We have prepared magnetic graphite samples bombarded by protons at low temperatures and low fluences to attenuate the large thermal annealing produced during irradiation. An overall optimization of sample handling allowed us to find Curie temperature
s $ T_c gtrsim 350$ K at the used fluences. The magnetization versus temperature shows unequivocally a linear dependence, which can be interpreted as due to excitations of spin waves in a two dimensional Heisenberg model with a weak uniaxial anisotropy.
