First principles electronic transport simulations of spin coherence length in disordered graphene nanoribbons due to spin-orbit interaction

Graphene presents high hopes for next-generation electronic applications. In particular, due to the small spin-orbit coupling in carbon one might envision using the electron's spin - instead of its charge - for information processing. In what has been dubbed Spintronics one of the main challenges, as one strives to obtain spin-based devices, is to obtain long spin coherence times (small spin relaxation) during electronic transport. Albeit the spin-coherence length in pristine graphene is deemed to be very large, the presence of defects and impurities can lead to spin-flips due to spin-orbit interactions. The presence of a large number of impurities randomly distributed in the system can, consequently, lead to the loss of spin-coherence. In this talk we will discuss spin-flip processes in disordered graphene nanoribbons containing a number of metal impurties. This will be achieved via a combination of Density Functional Theory - including Spin Orbit effects - with a recursive Green's function method to simulate the electronic transport of disordered systems. This way one is able to atomistically infer the spin-coherence length in graphene nanoribbons in the presence of defects or impurities. As a point in case I will show results for Ni adatoms.