RESEARCH ON BASIC TECHNOLOGIES FOR THE REALIZATION OF CATE CONTROLLED SPINTRANSISTOR

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High quality magnetite (Fe_3O_4) was found to be grown on (100) InAs surface. Magnetite film has become a candidate of high efficiency spin injector to be applied to spin transistor. On the other hand, we have also demonstrated gate controlled spin current oscillation due to spin-orbit interaction in Datta-Das type spin transistor structure based on Fe electrode and InAs-based heterostructure transistor at room temperature. In order to justify the observed experimental results of our spin FET characteristics, we have performed Monte Carlo Simulation taking account of Dyakonov - Perel mechanism. In a Datta-Das type spin transistor structure, it was found that vanishing of spin relaxation takes place when two spin orbit interaction, Rashba term and Dresselhaus term, equally contribute in InAs-based spin FET structure. Furthermore, it was found that the gate controlled spin precession takes place and resultant current oscillation should be observed even at room temperature when device operates in non-ballistic regime. Spin amplitude was also found to increase with the increase of lateral electric field (or drain voltage at given source drain distance). These predictions well explain what we have been observing in our Datta-Das type spin transistors. Other remarkable results include estimation of stay field near ferromagnetic electrode by micromagnetics calculation and thermal stability of iron/arsenide interface or thermodynamic calculation of stable compounds of iron and arsenic. Stray field near Fe wire film structure was found to be small except found in compounds such as As_2F (anti-ferro), AsF (anti-ferro), AsF_2 (normal metal) which well explains thermally unstable interface of Fe and InAs and suggests more stable spin injector material such as magnetite or iron silicide are suited for spin injector of spin FET.