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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 t-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. [ABSTRACT FROM AUTHOR]

Hall-effect and magnetoresistivity of holes in silicon and germanium are considered with due regard for mutual drag of light and heavy band carriers. Search of contribution of this drag shows that this interaction has a sufficient influence on both effects. [ABSTRACT FROM AUTHOR]

Hall-effect and magnetoresistivity of electrons in multi-valley bands of Si and Ge is considered with due regard for direct intervalley drag. Search of contribution of this drag shows that this interactioin sufficiently changes both effects. Calculated here values substantially differ from consequent those obtained on the base of popular τ-approximation. [ABSTRACT FROM AUTHOR]

The Seebeck coefficient α and Hall constant RH are calculated for monopolar crystal as based of quantum kinetic equation. It is shown that α and RH in the case of simple isotropic band do not depend on relaxation characteristics in contrast to the result obtained for the same crystals by calculations founded on relaxation time approximation. [ABSTRACT FROM AUTHOR]