Colloquia 2007

Colloquia 2007

A ‘Hole’ New Spin on Electronics

A/Professor Alex Hamilton
UNSW School of Physics

4-5 p.m., Tuesday, 11 September 2007

School of Physics Common Room
Room 64, Old Main Building

Conventional transistors rely on the charge of the electron to operate. However, in addition to their charge, electrons also possess a quantum mechanical spin, which offers potential for new device functionalities. For example, spin based transistors would consume much less power and operate much faster than their conventional counterparts. However there is much fundamental work to be done to understand how to control and manipulate spins in semiconductors.

I will present a gentle introduction to the origin of spin related phenomena in semiconductor nanostructures, and present the QED group’s recent work on p-type semiconductor nanostructures, in which electrical current is carried by holes, rather than electrons. Hole devices are particularly attractive for studying spin effects, as it is possible to use an electric field to manipulate the hole’s spin. We have recently developed the first high quality hole quantum wires that show clear quantisation of the ballistic resistance R=h/2ne2 [1, 2] and that confining the holes to a narrow quantum wire fundamentally alters their spin properties [3]. The spin anisotropy we observe can be understood in terms of a simple yet physical model of spin-orbit coupling. Most significantly we have exploited this spin anisotropy to shed new light on the anomalous “0.7 conductance quantisation feature” in 1D systems.

    • O. Klochan, W.R. Clarke, R. Danneau, A.P. Micolich, L.H. Ho, A.R. Hamilton, K. Muraki and Y. Hirayama, Ballistic transport in induced one--dimensional hole systems, Applied Physics Letters 89, 092105 (2006).
    • R. Danneau, W. R. Clarke, O. Klochan, A. P. Micolich, A. R. Hamilton, M. Y. Simmons, M. Pepper, and D. A. Ritchie, Conductance quantization and the 0.7×2e2/h conductance anomaly in one-dimensional hole systems, Applied Physics Letters 88, 012107 (2006).
    • R. Danneau, O. Klochan, W. R. Clarke, L.H. Ho, A. P. Micolich, M. Y. Simmons, A. R. Hamilton, M. Pepper, D. A. Ritchie,and U. Zuelicke, Zeeman splitting in ballistic hole quantum wires, Physical Review Letters, 97 026403 (2006)

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