Volume 94, Number 4, May 2011
|Number of page(s)||6|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||06 May 2011|
Magnetoresistance in disordered graphene: The role of pseudospin and dimensionality effects unraveled
CEA, INAC, SPRAM, GT - 17 rue des Martyrs, 38054 Grenoble Cedex 9, France, EU
2 IMEP-LAHC, UMR 5130 (Grenoble INP/UJF/CNRS/Université de Savoie), Minatec - 3 Parvis Louis Néel, 38016 Grenoble, France, EU
3 Laboratoire de Physique des Solides, UMR 8502 du CNRS, Université Paris-Sud - 91405 Orsay, France, EU
4 CIN2 (ICN-CSIC) and Universitat Autónoma de Barcelona, Catalan Institute of Nanotechnology, Campus de la UAB - 08193 Bellaterra (Barcelona), Spain, EU
5 ICREA, Institucio Catalana de Recerca i Estudis Avançats - 08010 Barcelona, Spain, EU
Accepted: 8 April 2011
We report a theoretical low-field magnetotransport study unveiling the effect of pseudospin in realistic models of weakly disordered graphene-based materials. Using an efficient Kubo simulation method, and simulating the effect of charges trapped in the oxide, different magnetoconductance fingerprints are numerically obtained for system sizes as large as 0.3 μm2, containing tens of millions of carbon atoms. In two-dimensional graphene, a strong valley mixing is found to irreparably yield a positive magnetoconductance (weak localization), whereas crossovers from positive to negative magnetoconductance (weak antilocalization) are obtained by reducing the disorder strength down to the ballistic limit. In sharp contrast, graphene nanoribbons with lateral size as large as 10 nm show no sign of weak antilocalization, even for very small disorder strength. Our results rationalize the emergence of a complex phase diagram of magnetoconductance fingerprints, shedding new light on the microscopical origin of pseudospin effects.
PACS: 72.80.Vp – Electronic transport in graphene / 72.15.Rn – Localization effects (Anderson or weak localization) / 73.63.-b – Electronic transport in nanoscale materials and structures
© EPLA, 2011
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