Quantum oscillations in graphene strutures
Abstract
The two-dimensional nature of the structure of graphite and carbon nanotubes, which are formed from graphene sheets leads to behaviour reminiscent of a two-dimensional electron gas. We observe quantum oscillations in both the magnetization (de Haas - van Alphen effect) and in the transport properties (Shubnikov - de Haas effect; quantum Hall effect) of highly-oriented pyrolytic graphite (HOPG) when the field is applied parallel to the c-axis. No oscillations could be resolved when the field was in the perpendicular direction. Multiwalled carbon nanotubes show an anomalous diamagnetic susceptibility, which is explained in terms of the occupancy of two Landau levels. De Haas - van Alphen oscillations are seen for randomly-oriented samples, but not for samples oriented with the field perpendicular to their axis. In both materials the quantum oscillations persist up to about 40 K. In neither case was a ferromagnetic magnetization associated with the carbon. The upper limit was 2 10-4 A m2 kg-1 for the nanotubes and 8 10-3 A m2 kg-1 for the HOPG.
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2004
- Bibcode:
- 2004APS..MARY26009S