Nanopicture of the Day

www.nanopicoftheday.org

March 15, 2004

Quantum Wire Electron Flow

Source:  George Krazcenow

      References:

G. Kirczenow, "Scattering Models of Conduction Around an Antidot in a Magnetic Field," Phys. Rev. B 50, 1649-1655 (1994).
 

A. S. Sachrajda, Y. Feng, R. P. Taylor, G. Kirczenow, L. Henning, J. Wang, P. Zawadzki and P. T. Coleridge, "Magnetoconductance of a Nanoscale Anti-Dot", Phys. Rev. B 50, 10856-10863 (1994).
 

Description:

The picture is a representation of the wave function of an electron traveling along a semiconductor quantum wire in a magnetic field and encountering a peanut-shaped artificial impurity or "antidot". It is based on a computer simulation by George Kirczenow of a device fabricated and studied experimentally by Andy Sachrajda and his collaborators at NRC in Ottawa. What you are seeing is an electron wave traveling from left to right along the top edge of the picture. When it hits the artificial impurity most of the electron wave is reflected, and then deflected downwards by the magnetic field towards the bottom of the antidot. There, most of the wave is again reflected and travels out of the picture from right to left along the bottom edge in a complicated interference pattern. But a small part of the wave leaks past the artificial impurity at the top and bottom. At the top this transmitted wave continues to the right in the form of the dark undulating ribbon. The transmitted wave at the bottom is deflected by the magnetic field and because of that returns to the top of the artificial impurity along the curved path on the right. Part of this path is darker and part is lighter than the background. Some of this returning wave then leaks back to the left above the artificial impurity, thus forming a closed resonant orbit whose signature is detected experimentally as a peak in the measured conductance of the device.
 

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