A selfconsistent calculation of the transport properties of a double barrier spin filter

Abstract

A double barrier resonant tunneling device in which the well is made of a semi-magnetic material can work as an effi cient spin fi lter. Today it is possible to make semiconductors that are ferromagnetic at room temperature. Therefore the device studied here has a great potential to be used as a polarizer, an analyzer and other spintronic applications. We discuss here the case of a Ga 1−x Mn x As/Ga 1−y Al y As system because it can be integrated into the well known AlGaAs/GaAs technology. Our tight-binding Hamiltonian includes the kinetic energy, the double-barrier profi le, the electric fi eld, the magnetic term, the hole-impurity and the hole-hole interactions. The profi le and the charge distribution are calculated self-consistently. In previous works we studied this system by solving the Hamiltonian in the reciprocal space, in order to simplify the treatment of the Poisson equation for the charge distribution. Here we introduce a simple one dimensional Green function that permits to solve all terms in the real space. Besides, a real space renormalization formalism is used to calculate exactly the electronic currents for each spin polarization. The results confi rm that the proposed system is a good device for spintronics.

Transport properties of a spin polarizer for electrons

“…In previous works we focused in the spin polarized transport of holes [10][11][12], however the spin relaxation time in quantum wells is approximately 100 ns for electrons and 150 ps for holes at T % 10 K [2,13]. Our device is a heterostructure whose configuration is 40Å À Ga 0:58 Al 0:42 As=93Å À Ga 0:95 Mn 0:05 As= 40ÅÀ Ga 0:58 Al 0:42 As, it is depicted in Fig.…”