A spin polarizer made of a diluted magnetic semiconductor quantum well

In this work we present results for the transport properties of a spin polarizer consisting of a resonant tunneling diode (RTD) in which the well is made of Ga1-xMnxAs. This is a diluted magnetic semiconductor (DMS) of p type. The magnetization of the well produces a splitting of the valence hand of approximately 0.15eV and consequently a splitting of resonant peaks. This 0.15 eV separation is bigger than the one produced by the highest stationary magnetic field obtained in a laboratory. As a consequence we get a spin polarized current when only one of these peaks is in between the Fermi level and the top of the valence band. We have considered heavy hole (HH) and light hole (LH) bands. The last one had not been considered in our previous works. Our system is described by a fight-binding Hamiltonian. The carriers interaction is calculated in the Hartree approximation. The charge distribution of the system and the potential profile are calculated self-consistently. Our results show that the system works as a very efficient spin filter. The magnetism and charge neutrality is mainly due to heavy holes. For a system with wide barriers, the spin polarized current is mainly due to light holes. (c) 2007 Elsevier B.V. All rights reserved.