Standing spin waves excited optically across an indirect gap in short graphene nanoribbons

Abstract

We report theoretical investigations that unveil unique electronic excitations in graphene nanoribbons of textit{nanoscale length}. The main point is that electronic states in short nanowires are standing particle-in-a-box-like waves, amenable to excitation by electromagnetic radiation; the unusual electronic and magnetic properties of graphene nanoribbons add another feature: terahertz (THz) radiation induces textit{edge standing spin waves} with different wavelengths at the two edges and a resonant frequency that can be controlled by an external gate voltage, opening the possibility of THz-spintronic applications.