Weak-localization magnetoresistance and valley symmetry in graphene.
Because of the chiral nature of electrons in a monolayer of graphite (graphene) one can expect weak antilocalization and a positive weak-field magnetoresistance in it. However, trigonal warping (which breaks p-->-p symmetry of the Fermi line in each valley) suppresses antilocalization, while intervalley 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.
McCann
E
E
Department of Physics, Lancaster University, Lancaster, LA1 4YB, United Kingdom.
Kechedzhi
K
K
Fal'ko
Vladimir I
VI
Suzuura
H
H
Ando
T
T
Altshuler
B L
BL