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Spin transport and dynamics in silicon-germanium islands (SDYSIGIS)
Date du début: 2 avr. 2010, Date de fin: 1 avr. 2012 PROJET  TERMINÉ 

"This project is centered on spin-dependent electronic transport and spin dynamics in self-assembled SiGe islands, directed at the development of semiconductor spintronic devices. In spite of its promising properties, SiGe remains a largely unexplored system for this purpose. The proposed project is further motivated and supported by an existing experience in the host group, which has recently succeeded in the realization of the first electronic devices based on individual SiGe quantum dots (QDs). Experimental effort will be first focused on the implementation of ferromagnetic (FM) contacts to the SiGe islands. Subsequently, low-temperature tunnel magnetoresistance (TMR) measurements will be performed as a function of the gate voltage and tunnel-coupling. The TMR response will provide important information concerning spin-injection efficiency and the impact of the Coulomb blockade phenomenon. Moreover, the effect of electric fields on the TMR response will be investigated, in order to identify signatures of Rashba spin-orbit interaction. To this end, dual-gate devices will be fabricated and their operation studied down to temperatures as low as 15 mK. Finally, the spin blockade regime will be exploited in order to explore the dynamics of single hole spins in SiGe islands. In particular, we aim to obtain important information on the characteristic time scales for spin relaxation and to perform coherent spin rotations by means of ac electric fields (via Rashba spin-orbit coupling). The proposed research project is also expected to create interesting opportunities for fundamental studies of exotic spin-related effects, resulting from the competition of ferromagnetic correlations, superconductivity, and Kondo effect."

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