Transport of Polarons in Graphene Nanoribbons.

The field-induced dynamics of polarons in armchair graphene nanoribbons (GNRs) is theoretically investigated in the framework of a two-dimensional tight-binding model with lattice relaxation. Our findings show that the semiconductor behavior, fundamental to polaron transport to take place, depends upon of a suitable balance between the GNR width and the electron-phonon (e-ph) coupling strength. In a similar way, we found that the parameter space for which the polaron is dynamically stable is limited to an even narrower region of the GNR width and the e-ph coupling strength. Interestingly, the interplay between the external electric field and the e-ph coupling plays the role to define a phase transition from subsonic to supersonic velocities for polarons in GNRs.