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Séminaire spécial MCBT

Lundi 2 décembre 2013 à 10h00
Salle Louis Weil, E424

Orateur : Makoto Kohda (Tohoku University, Japan)
"Spin Orbit Induced Stern-Gerlach Experiment in Semiconductor Nanostructures"


Stern-Gerlach experiment is one of the most beautiful experiments to show the spatial separation of spin angular momentum. Spin-up and spin-down angular momenta are accelerated opposite directions due to the spin dependent force caused by spatial modulation of external magnetic fields. Rashba spin-orbit interaction (SOI) induces an effective magnetic field, and thus the gate-controlled spin rotation was successfully demonstrated. Nevertheless, methods to create and detect spin polarization through the Rashba SOI have been still lacking. Here, I demonstrated electronic Stern-Gerlach experiment in a quantum point contact (QPC) by replacing the external magnetic field to the effective magnetic field induced by SOI [1]. An InGaAsP / InGaAs heterostructure with large Rashba SOI [2] was processed into trench-type QPCs with a top-gate electrode. In this SOI-coupled QPC, a spin-split conductance plateau is observed as 0.5(2e2/h) and spin polarization reaches 70% through the shot noise experiment. This achievement opens up a way to seamlessly integrate electrical spin generation, manipulation, and detection in a single semiconductor device without external magnetic field and magnetic materials.

[1] M. Kohda et al., Nature Communications 3, 1082 (2012).
[2] M. Kohda et al., Physical Review B 81, 115118 (2010).

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