To the problem of the intrinsic magnetism in carbon-based systems: pro et contra

TL;DR

This paper critically reviews evidence for and against intrinsic magnetism in carbon-based materials, concluding that experimental data largely show diamagnetism and that observed magnetic behaviors are likely due to impurities or defects.

Contribution

It provides a comprehensive analysis of experimental evidence, clarifying that pure graphene exhibits diamagnetism and that claims of intrinsic magnetism are unsubstantiated.

Findings

Pure graphene is strongly diamagnetic.

No ferromagnetism detected in pure graphene down to 2 K.

Magnetic signals are likely due to impurities or defects.

Abstract

The arguments supporting the existence of the intrinsic magnetism in carbon-based materials including pure graphene were analyzed critically together with the numerous experimental evidences denying the magnetism in these materials. The crucial experiment of Sepioni et al (Phys.Rev.Lett., v.105 p.207205 (2010)) showed clearly that no ferromagnetism was detected in pure graphene at any temperature down to 2 K. Neither do they found strong paramagnetism expected due to the massive amount of edge defects. 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.