by Staff Writers
Sydney, Australia (SPX) Jan 24, 2012
Physicists at the University of New South Wales have observed a new kind of interaction that can arise between electrons in a single-atom silicon transistor.
The findings, to be published this week in the journal Physical Review Letters, offer a more complete understanding of the mechanisms for electron transport in nanostructures at the atomic level.
"We have been able to study some of the most complicated transport mechanisms that can arise up to the single atom level," says lead author Dr Giuseppe C. Tettamanzi, from the School of Physics at UNSW.
The results contained in this study open the door for new quantum electronic schemes inwhich it is the orbital nature of the electrons - and not their spin or their charge - that plays a major role, he says.
The study, in collaboration with scientists from the ICMM in Madrid and the Kavli Institute in The Netherlands, describes how a single electron bound to a dopant atom in a silicon matrix can interact with many electrons throughout the transistor.
In these geometries, electron-electron interactions can be dominated by something called the Kondo effect. Conventionally, this arises from the spin degree of freedom, which represents an angular momentum intrinsic to each electron and is always in the up or in the down state.
However, researchers also observed that similar interactions could arise through the orbital degree of freedom of the electron. This describes the wave-like function of an electron and can be used to help determine an electrons' probable location around the atom's nucleus.
Importantly, by applying a strong magnetic field, the researchers were able to tune thiseffect to eliminate the spin-spin interactions while preserving the orbital-orbital interactions.
"By tuning the effect in two different symmetries of the fundamental state of the system...we have observed a symmetry crossover identical to those seen in high-energy physics," says Tettamanzi.
"In our case this crossover was observed simply by using a semiconductor device which is not too different from the transistor you use daily to send your emails."
Tettamanzi, who was recently awarded a prestigious ARC Discovery Early Career Researcher Award fellowship, will now investigate another transport mechanism that can arise in quantum dots and single atom transistors called "quantised charge pumping".
The idea here is to create a current flowing through a nanostructure without applying a voltage between the leads, but by applying varying potentials at one or more gates of the transistor, in an apparent violation of Ohm's law.
University of New South Wales
Computer Chip Architecture, Technology and Manufacture
Nano Technology News From SpaceMart.com
Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.
A big leap toward lowering the power consumption of microprocessors
Austin TX (SPX) Jan 23, 2012
The first systematic power profiles of microprocessors could help lower the energy consumption of both small cell phones and giant data centers, report computer science professors from The University of Texas at Austin and the Australian National University. Their results may point the way to how companies like Google, Apple, Intel and Microsoft can make software and hardware that will low ... read more
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2012 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|