Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Letting the spin loose

13.07.2005


A team of scientists at the Weizmann Institute of Science has recently demonstrated conclusively that, in very specific circumstances, spin can become separated from charge and progress independently down a wire



Two properties of an electron - its spin and its charge - are generally thought to be inseparable, intrinsic characteristics, no more given to sudden changes or going off on their own than say, the fur on a cat or the paint on a bicycle. But a team of scientists at the Weizmann Institute of Science has recently demonstrated conclusively that, in very specific circumstances, spin can become separated from charge and progress independently down a wire. Their findings appeared in a recent issue of Science.

Spin-charge separation was first predicted in the sixties. The idea was based on a theory that electrons with a range of movement limited to one dimension alone would behave differently from those moving in two or three dimensions. This is because when electrons are lined up head to tail, the influence of the repulsive forces between them becomes overridingly significant. But demonstrating the phenomenon had to wait until technology caught up to the theory.


Prof. Amir Yacoby of the Institute’s Condensed Matter Physics Department and research students Dr. Ophir Auslaender and Hadar Steinberg set up an experiment with quantum wires - so thin that electrons must go single file down their length, limiting flow to a single dimension and direction. "Up to a certain point, one can think of these electrons as cars on a narrow, one lane road: there’s no passing, and the slowest car sets the speed for the rest. A block in the road will bring all traffic to a halt. But here the analogy ends. If you increase car density on a road, traffic invariably slows down, while electrons speed along merrily in high-density flow and slow down when the density decreases. It is in these slow-moving, low density electron flows that things become interesting."

The separation the team achieved between spin and charge rests on the fact that the spins of electrons in these low density, single dimension flows generally follow a preferred arrangement: alternating between the two possible directions of electron spin - up and down. In the experiment, single electrons here and there could jump from wire to wire, allowing the scientists to jumble traffic a bit. So when an electron in the middle having, say, a down spin stepped out of the line, the next electron moved up to fill in, creating a situation with two neighboring ups. This non-ideal state of affairs caused one of them to flip its spin to down, which then caused the next electron, also with a down spin, to flip its spin to up, and so on. Thus the spin traveled down the wire independently of the charge, which stayed tied to the electrons.

Alex Smith | EurekAlert!
Further information:
http://www.jgordonassociates.com

More articles from Physics and Astronomy:

nachricht Breakthrough with a chain of gold atoms
17.02.2017 | Universität Konstanz

nachricht New functional principle to generate the „third harmonic“
16.02.2017 | Laser Zentrum Hannover e.V.

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>