Resonant enhancement and negative differential resistances in hybrid magnetic-electric barrier structures

We investigate electronic tunneling properties through hybrid magnetic-electric barriers under the influence of an external electric field. Two magnetic barrier configurations are analyzed: a single and a double delta (delta) function inhomogeneous magnetic field. The studies indicate that hybrid magnetic-electric barrier structures possess not only global features of both pure magnetic barriers and pure electric barriers but also some peculiar tunneling features. It is shown that there exist distinctive discrepancies in the transmission and the current density for electron traversing different magnetic configurations. To some extent, the transport behavior of the double delta-function configuration is similar to that of a square electric barrier while the single delta-function one resembles an electric step barrier. In addition, for electron tunneling through a hybrid magnetic-electric barrier with a single delta-function magnetic barrier, transmission resonances can be significantly enhanced by an external electric field, which results in distinctive negative-differential resistances with large peak-to-valley ratios in the spectrum of the current density. The results imply that one can tailor tunneling properties in hybrid magnetic-electric barriers by means of adjusting the distribution and the strength of the inhomogeneous magnetic field.