X iv : c on d - m at / 0 41 13 54 v 1 [ co nd - m at . o th er ] 1 2 N ov 2 00 4 RESONANCE SPIN FILTER

During last years the world-community of nano-electronics is engaged in a search of new physical principles, materials and technologies on which the quantum spin-transistor may be manufactured [1]. This anticipated device could become a base of the toolbox of quantum computations and help testing the constructions of various quantum networks. Basic principle of the spin-transistor was suggested in the paper [1]. The leading idea of the proposal is the use of the spin-orbital interaction [2] for creation of the spin-polarized current in the transistor channel. Actually, to produce a real device based on the above mentioned principle one should: 1. select proper material with maximal spin-orbital interaction causing a considerable spin-orbital splitting, 2. suggest a method of introduction and withdrawal of electrons with certain spin polarization. An extended analysis of experimental and theoretical ideas leading to the solution of the first problem was suggested in the pioneering paper [3]. According to [4, 5, 6] the maximal spin splitting may appear in semiconductors with Kane dispersion for spectral bands. The magnitude of splitting is bigger for materials with smaller Kane gap, see [7]. Generically, the spin-orbital splitting is two times bigger in the semiconductors with inverse band structure, compared with other semiconductors, see [6, 8]. In the simplest phenomenological Rashba model for the non-symmetric quantum well the corresponding additional linear term with Rashba parameter α is added to the quadratic kinetic term: E ± = ¯ h 2 k 2 2m ± αk. (1) The Rashba parameter α is defined by the band structure of the material, in particular by the magnitude ∆ R of the gap, by the quasi-momentum, by the electrostatic potential V (z) forming 2D-electron gas and by the shape of the wave-functions of 2d electrons. According to [3, 4, 5] both the theory and the experiment vote in favor of materials Cd Hg Te, where ∆ R circa 40 − 60 meV, and the magnitude of the effective Rashba parameter is about (0.2 − 0.3)10 −10 ev/m. This is approximately 10 times bigger, that the parameter α in other hetero-structures studied before : ∆ R ≈ (0.02 : 5) meV and α ≈ (10 −12 − 10 −11) eV m. We guess that such materials as Cd Hg Te are most prospective for the high-temperature Spintronics. Analysis done in [5, 6, 8] shows that large values of spin-orbital splitting are also achieved for InAs and HgTe. All …