  We examine the possibility of using graphene nanoribbons (GNRs) with directly
substituted chromium atoms as spintronic device. Using density functional
theory, we simulate a voltage bias across a constructed GNR in a device setup,
where a magnetic dimer has been substituted into the lattice. Through this
first principles approach, we calculate the electronic and magnetic properties
as a function of Hubbard U, voltage, and magnetic configuration. By calculating
of the total energy of each magnetic configuration, we determine that initial
antiferromagnetic ground state flips to a ferromagnetic state with applied
bias. Mapping this transition point to the calculated conductance for the
system reveals that there is a distinct change in conductance through the GNR,
which indicates the possibility of a spin valve. We also show that this
corresponds to a distinct change in the induced magnetization within the
graphene.
