Current-Controlled Spin Flip in Magnetically-Substituted Graphene Nanoribbons: Toward the Realization of Graphene-Based Spintronic Devices

We examine the possibility of using graphene nanoribbons with directly substituted chromium atoms as spintronic device. Using density functional theory, we simulate a voltage bias across a constructed graphene nanoribbon in a device setup, where a magnetic dimer has been substituted into the lattice. Using a first principles approach, we calculate the electronic and magnetic properties as a function of Hubbard U, voltage, and magnetic configuration. Through a calculation of the energy of each magnetic configuration, we can 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 graphene nanoribbon, 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. Our goal is to show that graphene, while already being used in electronic, may also have spintronic capabilities as well.