McCann, Edward and Kechedzhi, K. and Fal’ko, Vladimir I. and Suzuura, H. and Ando, T. and Altshuler, B. L. (2006) Weak localisation magnetoresistance and valley symmetry in graphene. Physical Review Letters, 97 (14). p. 146805. ISSN 1079-7114
Due to the chiral nature of electrons in a monolayer of graphite (graphene) one can expect weak antilocalisation and a positive weak-field magnetoresistance in it. However, trigonal warping (which breaks p to −p symmetry of the Fermi line in each valley) suppresses antilocalisation, while inter-valley scattering due to atomically sharp scatterers in a realistic graphene sheet or by edges in a narrow wire tends to restore conventional negative magnetoresistance. We show this by evaluating the dependence of the magnetoresistance of graphene on relaxation rates associated with various possible ways of breaking a ’hidden’ valley symmetry of the system.
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