ABSTRACT
Graphene nanoribbons display an imperfectly understood transport gap. We measure transport through nanoribbon devices of several lengths. In long (>/=250 nm) nanoribbons we observe transport through multiple quantum dots in series, while shorter (
Subject(s)
Crystallization/methods , Graphite/chemistry , Models, Chemical , Nanostructures/chemistry , Nanostructures/ultrastructure , Nanotechnology/methods , Quantum Dots , Computer Simulation , Macromolecular Substances/chemistry , Materials Testing , Molecular Conformation , Particle Size , Surface PropertiesABSTRACT
We measure the differential conductance of a single-electron transistor (SET) irradiated with microwaves. The spin-entangled many-electron Kondo state produces a zero-bias peak in the dc differential conductance if the quantum dot in the SET contains an unpaired electron. When the photon energy hf is comparable to the energy width of the Kondo peak and to e (the charge on the electron) times the microwave voltage across the dot, satellites appear in the differential conductance shifted in voltage by +/-hf/e from the zero-bias resonance. We also observe an overall suppression of the Kondo features with increasing microwave voltage.