Zero bias anomalies due to magnetically doped tunnel barriers

Abstract

The miniband transport in semiconductor superlattices under the influence of high electric and magnetic fields aligned parallel to the superlattice axis is treated within a rigorous quantum-mechanical approach. Intra-collisional field effects due to the electric and magnetic field are taken into account. Pronounced resonances are predicted to occur in the current density due to Landau and Wannier–Stark quantization of the electronic states and due to their scattering on polar-optical phonons. The combined electric and magnetic field effects are treated by a non-equilibrium lateral electron distribution function, which is the solution of a quantum-kinetic equation. The field-dependent coupling between longitudinal and transverse degrees of freedom via the lateral distribution function leads to a non-separable dependence of the current on the electric and magnetic fields. Wannier–Stark current oscillations are strongly enhanced by high magnetic fields. The experimentally detected crossover in the temperature dependence of the current is reproduced. Finally, the influence of an electric field on magneto-phonon resonances is studied.