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Abstract: A theoretical study of the magnetoelectronic properties of zigzag andarmchair bilayer graphene nanoribbons BGNs is presented. Using the recursiveGreen-s function method, we study the band structure of BGNs in uniformperpendicular magnetic fields and discuss the zero-temperature conductance forthe corresponding clean systems. The conductance quantized as 2n+1G for thezigzag edges and nG 0 for the armchair edges with G {0}=2e^2-h being theconductance unit and $n$ an integer. Special attention is paid to the effectsof edge disorder. As in the case of monolayer graphene nanoribbons GNR, asmall degree of edge disorder is already sufficient to induce a transport gaparound the neutrality point. We further perform comparative studies of thetransport gap E g and the localization length in bilayer and monolayernanoribbons. While for the GNRs E {g}^{GNR}is proportional to 1-W, thecorresponding transport gap E {g}^{BGN} for the bilayer ribbons shows a morerapid decrease as the ribbon width W is increased. We also demonstrate that theevolution of localization lengths with the Fermi energy shows two distinctregimes. Inside the transport gap, xi is essentially independent on energy andthe states in the BGNs are significantly less localized than those in thecorresponding GNRs. Outside the transport gap \xi grows rapidly as the Fermienergy increases and becomes very similar for BGNs and GNRs.



Autor: Hengyi Xu, T. Heinzel, I. V. Zozoulenko

Fuente: https://arxiv.org/







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