Anomalous paramagnetism in doped carbon nanostructures

A systematic study of the magnetic properties of corrugated and noncorrugated carbon nanotori doped with different ratios of extra electrons or holes to stimulate the effect of charge transfer using nonmagnetic elements, is presented. The corrugated systems were constructed by coalescing C₆₀ molecules along the three axes of symmetry, and non-corrugated systems were constructed by joining and relaxing the two ends of open-ended carbon nanotubes. The difference between the highest occupied molecular orbital (HOMO) level and the lowest unoccupied molecular orbital (LUMO) was considered as the electronic gap. It was observed that the carbon systems with an electronic open shell can exhibit huge paramagnetic ring currents. Carbon tori exhibiting a half-filled HOMO level display the largest local ring currents.