In this work we investigate the carrier transport through Datta and Das spin-modulator devices. We calculate the transmission coefficient of spin-polarized electrons taking into account their reflection from both ferromagnetic contacts. We show that the interfaces make the device behave as a Fabry-Perot cavity, so that Breit-Wigner resonances appear in the transmission coefficient. Moreover, interference of quantum-confined electron states with free electron states leads to appearance of asymmetric Fano-type resonances. These resonances can be seen in the conductivity dependence on the chemical potential in the channel at very low temperatures $(<1\mathrm{K})$.

• Received 5 April 2004

DOI:https://doi.org/10.1103/PhysRevB.70.205328