  We propose a model describing the evolution of the free electron current
density in graphene.
  Based on the concept of Mp-branes, we perform the analysis using the
difference between curvatures of parallel and antiparallel spins. In such a
framework an effective graviton emerges in the form of gauge field exchange
between electrons. In a plain graphene system, the curvatures produced by both
kinds of spins neutralize each other. However, in the presence of defects, the
inequality between curvatures leads to the emergence of current density,
modified gravity and conductivity. Depending on the type of the defects, the
resulting current density can be negative or positive.
