Effect of the interlayer interactions on the diamagnetism of graphitic ribbons

Abstract

The temperature dependence of the magnetic susceptibility of pregraphitic carbons is calculated using London's theory applied to a three-dimensional lattice where the diamagnetism is a function of the carbon size. In the case of a two-dimensional model of a graphitic ribbon, the diamagnetism per mass is proportional to the ribbon width $L$ within the limit of approximation. In the case of a three-dimensional model, the diamagnetism per mass is proportional to $L$ when the lattice is smaller than 100 \AA{} and it becomes constant when $L$ is larger than 300 \AA{}. The critical $L$ values are roughly a function of $\frac{{\ensuremath{\beta}}^{0}}{{\ensuremath{\gamma}}^{1}}$ where the resonance integral parameters ${\ensuremath{\beta}}^{0}$ and ${\ensuremath{\gamma}}^{1}$, respectively, describe the interactions of two neighboring atoms in the same layer and in two neighboring layers.