ELECTRONIC AND TRANSPORT PROPERTIES OF ARMCHAIR GRAPHENE NANORIBBON JUNCTIONS INVOLVING ZIGZAG EDGE INTERFACES

Abstract

IN A JUNCTION WITH AN ARMCHAIR RIBBON (AGNR) SANDWICHED IN-BETWEEN TWO WIDER AGNR-LEADS AND INCORPORATING ZIGZAG-EDGE INTERFACES, WE FIND FROM FIRST-PRINCIPLES CALCULATIONS TWO STATES WITH ENERGY UNUSUALLY INDEPENDENT OF THE AGNR LENGTH. SUCH STATES MAKES THE JUNCTIONS PERFECT MOLECULAR WIRES WITH CONDUCTANCE REMAINS CONSTANT AS WIRE LENGTHENS. THE LENGTH-INDEPENDENT BEHAVIOR CAN BE DIRECTLY DERIVED FROM THE WAVEFUNCTION PATTERN CONTAINING LOCALLY REPEATING UNITS. THE LENGTH BECOMES UNIMPORTANT BECAUSE STATES ARE NOT CONFINED WITHIN THE AGNR, DUE TO THE ZIGZAG EDGES SERVING AS ELECTRON SOURCES. WE FURTHER FIND THESE STATES ORIGINATE FROM EXTENSION OF THE ZIGZAG EDGE STATE INTO THE AGNR. DEPENDING ON THE WIDTH OF AGNR, THE EXTENSION CAN BE NON-DECAYING OR SHOWING A DECAY RATE. IN ADDITION, WE DEMONSTRATE THESE STATES CAN BE TUNED WITH A MAGNETIC FIELD TO GIVE MAGNETORESISTANCE REACHING ~900%. THEY CAN ALSO BE DRIVEN INTO THE GAP OF AGNR-LEADS USING A BIAS TO INDUCE A NEGATIVE DIFFE