Ballistic magnetotransport and field-induced interaction effects in graphene.

A weak perpendicular magnetic field, B, breaks the chiral symmetry of each valley in the electron spectrum of graphene, preserving the overall chiral symmetry in the Brillouin zone. We explore the consequences of this symmetry breaking for the interaction effects in graphene. In particular, we demonstrate that: 1) the electron-electron interaction lifetime acquires an anomalous B-dependence. Also, the ballistic zero-bias anomaly emerges at a weak B that has an algebraic form. 2) The perpendicular magnetic field introduces an anomalous interaction correction to the static conductivity of doped graphene in the ballistic regime. The correction implies that the magnetoresistance scales inversely with temperature $\prop 1/T$ in a parametrically large interval. When the disorder is scalar-like, the $\prop 1/T$ behavior is the leading contribution in the crossover between diffusive regime exhibiting weak localization and quantum magneto-oscillations. 3) Temperature dependence of the magnetic-field corrections to the thermodynamic characteristics of graphene is also anomalous.