  In this report we have pointed out that magnetic hysteresis loop can be used
as a probe to distinguish a single layer from a many layer graphitic structure.
Chemically we have synthesized graphitic oxide (GO) and reduced graphitic oxide
(RGO) for this investigation. We observe ferromagnetic like hysteresis loops
for both GO and RGO below a certain applied critical magnetic field and above
this critical field we observe cross-over of the positive magnetization to
negative magnetization leading to diamagnetic behaviour. This cross-over is
more dominant for the case of many layer graphitic structure. Upon annealing of
GO in air the critical cross-over field decreases and the magnetization
increases for multilayer graphitic structure. Possible reasons for all these
observations and phenomena is presented here.
