Transport phenomena of two-dimensional band carriers with Dirac-like energetic spectrum

Abstract

Conductivity of monolayer and bilayer graphene is considered with due regard for mutual drag of band electrons and holes. Search of contribution of the drag to conductivity shows that it sufficiently influences on mobility at high concentrations of carriers, which belong to different groups and have different drift velocities. In bilayer system the mutual drag can even change the direction of partial current. Magnetoresistivity and Hall effect were theoretically investigated for neutral and gated graphene. It is shown that for spatially unlimited neutral graphene Hall effect is totally absent. In gated, exactly monopolar graphene for the same case effect of magnetoresistivity vanishes; here the Hall constant does not involve any relaxation characteristic in contrast to results obtained for the popular method of τ-approximation. It is shown that limited sizes of crystal with monopolar conductivity can be cause for impressive dependence of the Hall constant and magnetoresistivity on the value of external magnetic field.