VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013

 QNplage

 Nanophysics: from fundamentals to applications

(the return)

 

Wednesday 7
Graphene

› 14:20 - 14:40 (20min)
Unveiling the Landau Levels Structure of Graphene Nanoribbons
Rebeca Ribeiro  1, *@  , Jean-Marie Poumirol  1@  , Alessandro Cresti  2@  , Walter Escoffier  1@  , Michel Goiran  1@  , Jean-Marc Broto  1@  , Stephan Roche  3@  , Bertrand Raquet  1@  
1 : Laboratoire national des champs magnétiques intenses - Toulouse  (LNCMI)  -  Website
CNRS : UPR3228
143 avenue de Rangueil 31400 Toulouse -  France
2 : Institut de Microélectronique, Electromagnétisme et Photonique - Laboratoire d'Hyperfréquences et Caractérisation  (IMEP-LAHC)
CNRS : UMR5130, Université Joseph Fourier - Grenoble I, Institut National Polytechnique de Grenoble - INPG, Université de Savoie, Institut National Polytechnique de Grenoble (INPG)
Minatec-INPG 3 parvis Louis Néel BP 257 38016 GRENOBLE CEDEX 1 -  France
3 : Institució Catalana de Recerca i Estudis Avançats [Barcelona]  (ICREA)  -  Website
Passeig Lluís Companys, 23 08010 Barcelona - Espanya -  Spain
* : Corresponding author

Carbon-based systems are one of the most promising topics of nano-electronics. The challenging task for technologists is the achievement of clean devices with an engineered energy gap. The lateral confinement in graphene nanoribbons leads to a series of 1D electronic subbands with a confinement gap. In presence of a large enough magnetic field, the band structure is expected to evolve into magneto-electric subbands with fingerprints of the edge symmetry (armchair or zigzag). The goal of our study is to play with a strong magnetic confinement to give evidence of the peculiarity of the electronic structure of GNRs, driven by edge structure.

Here, we present experimental results obtained in lithographically patterned GNRs which present high carrier mobility and a weakly diffusive transport regime. In wide ribbons (W=100 nm) magneto-resistance measurements show experimental evidence of Hall quantization in GNRs for filling factors n=2 and 6. On the other hand, anomalies in the SdH oscillations, at high doping level, give evidence of the electronic confinement effects [1]. When we consider narrower ribbons new quantum oscillations develop in the Landau spectrum. These new spectra directly compared to magneto-electric subbands calculations, is assigned to a possible valley degeneracy lifting driven by the confining potential in presence of armchair symmetry at the edges [2].

[1] N. Peres et al. PRB 73, 241403 (2006)

[2] R. Ribeiro et al. PRL 107, 086601 (2011)


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