Magnetotransport in ferromagnetic resonant tunnelling diodes

We have studied theoretically the magnetotransport in ferromagnetic resonant tunnelling diodes (FRTDs), where alternating magnetic Ga1-xMnxAs and non-magnetic GaAs and AlAs layers give rise to strongly spin-polarization-dependent electronic transport. We have studied two cases: (1) an FRTD structure with a non-magnetic quantum well between magnetic emitter and collector layers, and equation (2) an FRTD structure with a ferromagnetic quantum well between non-magnetic emitter and collector layers. First a correction to the energy of the band edge due to the exchange interaction between the charge carrier spin and the magnetic moments of the Mn ions is estimated. Then the current-voltage characteristics of the FRTD are calculated as a function of temperature and magnetic field using a modified Tsu-Esaki formula. In the FRTD the transport depends strongly on the spin polarization of the magnetic lattice, and in a certain bias voltage range near the negative resistance region the model predicts colossal magnetoresistance at temperatures close to the Curie temperature. (author)