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Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities
Published on: July 24, 2015
Limits on intrinsic magnetism in graphene
M Sepioni1, R R Nair, S Rablen
1Manchester Centre for Mesoscience & Nanotechnology, University of Manchester, Manchester M13 9PL, United Kingdom.
Physical Review Letters
|January 15, 2011
Summary
Graphene nanocrystals are strongly diamagnetic, not ferromagnetic, with a weak paramagnetic signal from specific defects below 50 K. This study clarifies the magnetic properties of exfoliated graphene nanomaterials.
Area of Science:
- Materials Science
- Condensed Matter Physics
- Nanotechnology
Background:
- Graphene, a single layer of carbon atoms, exhibits unique electronic and magnetic properties.
- Graphene nanocrystals are synthesized via sonic exfoliation of graphite.
- The presence of edge defects in graphene is often associated with expected paramagnetism.
Purpose of the Study:
- To investigate the magnetization properties of graphene nanocrystals.
- To determine the presence or absence of ferromagnetism and significant paramagnetism.
- To identify the source of any observed magnetic contributions.
Main Methods:
- Sonic exfoliation of graphite to obtain graphene nanocrystals.
- Magnetization measurements conducted at various temperatures down to 2 Kelvin.
- Analysis of magnetic data to identify defect contributions.
Main Results:
- No ferromagnetism was detected in graphene nanocrystals at any temperature.
- Strong diamagnetism, characteristic of graphite, was observed.
- A weak paramagnetic contribution, noticeable below 50 K, was identified.
- A single type of defect was found responsible for the paramagnetism, with one magnetic moment per crystallite.
Conclusions:
- Graphene nanocrystals are predominantly diamagnetic.
- The expected strong paramagnetism from edge defects is not observed.
- A specific defect species accounts for the weak low-temperature paramagnetism in these graphene nanomaterials.
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