31 research outputs found
Magnetic field screening and mirroring in graphene
The orbital magnetism in spatially varying magnetic fields is studied in
monolayer graphene within the effective mass approximation. We find that,
unlike the conventional two-dimensional electron system, graphene with small
Fermi wave number k_F works as a magnetic shield where the field produced by a
magnetic object placed above graphene is always screened by a constant factor
on the other side of graphene. The object is repelled by a diamagnetic force
from the graphene, as if there exists its mirror image with a reduced amplitude
on the other side of graphene. The magnitude of the force is much greater than
that of conventional two-dimensional system. The effect disappears with the
increase of k_F.Comment: 5 pages, 3 figure
Electron-electron interaction in carbon nanostructures
The electron-electron interaction in carbon nanostructures was studied. A new
method which allows to determine the electron-electron interaction constant
from the analysis of quantum correction to the magnetic
susceptibility and the magnetoresistance was developed. Three types of carbon
materials: arc-produced multiwalled carbon nanotubes (arc-MWNTs), CVD-produced
catalytic multiwalled carbon nanotubes (c-MWNTs) and pyrolytic carbon were used
for investigation. We found that =0.2 for arc-MWNTs (before and
after bromination treatment); = 0.1 for pyrolytic graphite;
0 for c-MWNTs. We conclude that the curvature of graphene layers
in carbon nanostructures leads to the increase of the electron-electron
interaction constant .Comment: 12 pages, 18 figures, to be published in the Proceedings of the NATO
Advanced Research Workshop on Electron Correlation in New Materials and
Nanosystems, NATO Science Series II, Springer, 200
Comparison of the In-plane Thermal and Electrical Conductivities and Transverse Pull Strengths of Various Pyrolytic Graphite Materials
Different pyrolytic graphite materials were produced varying the annealing parameters such as temperature, pressure and time. These variations should alter the product properties in a systematic way. The coefficient of in-plane thermal conductivity, C_KT, the coefficient of electrical conductivity, and the pull strength S of these samples were measured. Results for the different materials and correlations are reporte