VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013


 Nanophysics: from fundamentals to applications

(the return)


Friday 9
Dots and wires

› 11:30 - 12:00 (30min)
Unusual spin properties of holes in GaAs nanostructures
Alex Hamilton  1@  
1 : The University of New South Wales (AUSTRALIA)  (UNSW)  -  Website
School of Physics, University of NSW, Sydney 2052, Australia -  Australia

The electrical current in a semiconductor can be carried by negatively charged electrons or positively charged holes. In undergraduate physics, we are often taught 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, particularly when confined to low dimensions. In this talk I will show that although most computer chips contain billions of nanoscale hole transistors, there is some way to go yet before we have a complete understanding of their quantum properties.

The differences between electrons and holes show up as highly anisotropic spin properties. I will review some of our results from high quality p-type semiconductor nanostructures, where holes can be confined to two-dimensional sheets, one-dimensional quantum wires and zero-dimensional dots [1,2]. 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, with g-factors ranging from $g*=5$ to g smaller than 0.4

We have also studied spin-3/2 holes in GaAs quantum dots, which are of interest for quantum computing applications since hole spins are much less susceptible to unwanted dephasing from the nuclear spins of the Ga and As atoms [6].

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