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The interest for semiconductors with large spin-orbit interactions (SOI)
arises from the possibility to manipulate the electronic spin using an
electric field. Although p-type GaAs and InAs are known as appropriate
systems for studying the spin-orbit coupling, few experiments have been
realized in these systems due to the difficulty to fabricate nanostructures.
Here we show the influence of SOI on quantum transport in quantum dots in
InAs, and through a ring in p-type GaAs.
For electrons trapped in quantum dots, SOI could provide a way to coherently manipulate single electron spin using simple electrostatic gates. We have realized tunable double quantum dots (DQD) in InAs nanowires. By measuring electronic transport through the DQD, we identify spin states for which Pauli principle leads to a suppression of the current. Associating this technique with fast gate manipulation, we study spin relaxation and decoherence in this system with strong SOI. Coherent transport through a nanostructure is also influenced by SOI: in a material with strong SOI an electron (hole) acquires a geometrical phase which could be tuned with an electric field. In order to identify this phase, we have realized a ring structure in p-type GaAs, where we observe Aharonov-Bohm oscillations. A clear beating of the AB oscillations, associated with a phase shift at the node, is a strong indication of the influence of SOI on the electronic phase. |
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