Density matrix approach to electron transport in an arbitrary magnetic field and negative magnetoresistance

Abstract

A solution of a kinetic equation for the one-particle density matrix is obtained for deformation potential scattering. Expressions for conductivity tensor components as sums over states in a magnetic field are derived. It is shown that without a magnetic field they do not differ from classical expressions. In a weak magnetic field, the magnetoresistance of a nondegenerate electron gas is positive for high electron mobility and negative for low mobility. For intermediate mobility, its sign changes with the magnetic-field increase. The magnetoresistance of a degenerate electron gas is nonzero. In a quantizing magnetic field, the conductivity oscillates as a function of the magnetic field. The oscillation amplitude and the mean magnetoresistance value increase with the magnetic field or mobility growth.