Unconventional and Exotic Magnetism in Carbon-Based Structures and Related Materials

TL;DR

This paper critically examines claims of magnetism in carbon-based materials, especially graphene, concluding that observed magnetic behaviors are likely due to impurities or defects rather than intrinsic magnetism, emphasizing the need for thorough experimental studies.

Contribution

The paper provides a critical analysis of previous claims of magnetism in carbon structures, clarifying misconceptions and emphasizing the importance of rigorous experiments to understand their magnetic properties.

Findings

Graphene is strongly diamagnetic, not ferromagnetic.

Previous reports of ferromagnetism in graphene are likely incorrect.

Impurities and defects may induce magnetic-like behavior in carbon materials.

Abstract

The detailed analysis of the problem of possible magnetic behavior of the carbon-based structures was fulfilled to elucidate and resolve (at least partially) some unclear issues. It was the purpose of the present paper to look somewhat more critically into some conjectures which have been made and to the peculiar and contradictory experimental results in this rather indistinct and disputable field. Firstly the basic physics of magnetism was briefly addressed. Then a few basic questions were thoroughly analyzed and critically reconsidered to elucidate the possible relevant mechanism (if any) which may be responsible for observed peculiarities of the "magnetic" behavior in these systems. The arguments supporting the existence of the intrinsic magnetism in carbon-based materials, including pure graphene were analyzed critically. It was concluded that recently published works have shown clearly that the results of the previous studies, where the "ferromagnetism" was detected in pure graphene, were incorrect. Rather, graphene is strongly diamagnetic, similar to graphite. Thus the possible traces of a quasi-magnetic behavior which some authors observed in their samples may be attributed rather to induced magnetism due to the impurities, defects, etc. On the basis of the present analysis the conclusion was made that the thorough and detailed experimental studies of these problems only may shed light on the very complicated problem of the magnetism of carbon-based materials. Lastly the peculiarities of the magnetic behavior of some related materials and the trends for future developments were mentioned.