  Magnetic graphene-ribbon is a candidate for realizing future ultra high
density 100 tera bit/inch2 class data storage media. Multiple spin state
analysis was done based on the density function theory. A typical model was a
super cell [C80H7] which having bare (radical) carbons on one side zigzag edge,
whereas mono hydrogenated on another side. Optimizing atomic configuration,
self consistent calculation demonstrated that a total energy of the highest
spin state is more stable than that of lower one, which came from exchange
coupling between carbons. This analysis suggested a capability of designing
magnetic data track utilizing such chemically edge modified graphene ribbon. In
order to increase areal magnetization density, bilayer and quadri-layer
graphene-ribbon model were analyzed. Detailed calculation resulted that also
the highest spin state is the most stable one. Multiplying the layer numbers is
effective way to realize and enhance strong magnetism.
