Accueil du site Séminaires Séminaire QUEST

Séminaire QUEST

Jeudi 15 décembre à 9h30,
Salle Rémy Lemaire, K223

Orateur : Alex Hamilton, University of New South Wales (Australia)
"Strange properties of spin-3/2 holes in semiconductor nanostructures"


The electrical current In a semiconductor can be carried by negatively charged electrons or positively charged holes. In undergraduate physics, we are tell students that holes in the valence band are just an absence of an electron. But they aren’t. Valence band holes are spin-3/2 particles, and this gives them very different properties to spin-1/2 electrons. In recent years there has been growing theoretical interest in the possibility of using holes in semiconductor nanostructures for applications ranging from ultra-fast spin transistors through to quantum information and communication. This talk will describe where holes come from, why they are so different to electrons, and what one can do with holes that can’t be done with electrons.
The differences between electron and holes are most striking when they are confined to low dimensional nanostructures. I will present two examples :
(i) In quantum wires the interplay of spin-orbit interaction and electrostatic confinement leads to an extreme anisotropy of the Zeeman spin-splitting that is completely unlike electrons, and still not fully understood.
(ii) I will also present new data showing that we can make devices that perform the solid-state equivalent of the Stern-Gerlach experiment in atomic physics, and use these to separate spins without the need for large gradients of the magnetic field.
These results have implications for spin-based electronics and quantum information processing with valence band holes.

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