Comment on: "Revealing common artifacts due to ferromagnetic inclusions in highly oriented pyrolytic graphite", by M. Sepioni, R.R. Nair, I.-Ling Tsai, A.K. Geim and I.V. Grigorieva, EPL 97 (2012) 47001

TL;DR

This comment challenges the claim that ferromagnetism in pristine HOPG is due to impurities, providing arguments and citing microscopic evidence that supports its intrinsic origin.

Contribution

It refutes prior assertions by presenting evidence and arguments that support the intrinsic ferromagnetism in pristine HOPG, countering impurity-based explanations.

Findings

XMCD measurements confirm intrinsic ferromagnetism in HOPG.

Impurity contamination is not the primary cause of ferromagnetism.

Previous claims attributing ferromagnetism to impurities are challenged.

Abstract

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 contamination. 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.