Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > At Small Scales, Tug-of-War Between Electrons Can Lead to Magnetism Under Surprising Circumstances

Theoretical physicist Igor Zutic and colleagues hope to create a quantum dot that is magnetic.
Theoretical physicist Igor Zutic and colleagues hope to create a quantum dot that is magnetic.

Abstract:
At the smallest scales, magnetism may not work quite the way scientists expected, according to a recent paper in Physical Review Letters by Rafal Oszwaldowski and Igor Zutic of the University at Buffalo and Andre Petukhov of the South Dakota School of Mines and Technology.

At Small Scales, Tug-of-War Between Electrons Can Lead to Magnetism Under Surprising Circumstances

Buffalo, NY | Posted on June 29th, 2011

The three physicists have proposed that it would be possible to create a quantum dot -- a kind of nanoparticle -- that is magnetic under surprising circumstances.

Magnetism is determined by a property all electrons possess: spin. Individual spins are akin to tiny bar magnets, which have north and south poles. Electrons can have an "up" or "down" spin, and a material is magnetic when most of its electrons have the same spin.

Mobile electrons can act as "magnetic messengers," using their own spin to align the spins of nearby atoms. If two mobile electrons with opposite spins are in an area, conventional wisdom says that their influences should cancel out, leaving a material without magnetic properties.

But the UB-South Dakota team has proposed that at very small scales, magnetism may be more nuanced than that. It is possible, the physicists say, to observe a peculiar form of magnetism in quantum dots whose mobile electrons have opposing spins.

In their Physical Review Letters article, the researchers describe a theoretical scenario involving a quantum dot that contains two free-floating, mobile electrons with opposite spins, along with manganese atoms fixed at precise locations within the quantum dot.

The quantum dot's mobile electrons act as "magnetic messengers," using their own spins to align the spins of nearby manganese atoms.

Under these circumstances, conventional thinking would predict a stalemate: Each mobile electron exerts an equal influence over spins of manganese atoms, so neither is able to "win."

Through complex calculations, however, Oszwaldowski, Zutic and Petukhov show that the quantum dot's two mobile electrons will actually influence the manganese spins differently.

That's because while one mobile electron prefers to stay in the middle of the quantum dot, the other prefers to locate further toward the edges. As a result, manganese atoms in different parts of the quantum dot receive different messages about which way to align their spins.

In the "tug-of-war" that ensues, the mobile electron that interacts more intensely with the manganese atoms "wins," aligning more spins and causing the quantum dot, as a whole, to be magnetic. (For a visual representation of this tug-of-war, see Figure 1.)

This prediction, if proven, could "completely alter the basic notions that we have about magnetic interactions," Zutic says.

"When you have two mobile electrons with opposite spins, the assumption is that there is a nice balance of up and down spins, and therefore, there is no magnetic message, or nothing that could be sent to align nearby manganese spins," he says. "But what we are saying is that it is actually a tug of war. The building blocks of magnetism are still mysterious and hold many surprises."

Scientists including UB Professor Athos Petrou, UB College of Arts and Sciences Dean Bruce McCombe and UB Vice President for Research Alexander Cartwright have demonstrated experimentally that in a quantum dot with just one mobile electron, the mobile electron will act as a magnetic messenger, robustly aligning the spins of adjacent manganese atoms.

Now, Petrou and his collaborators are interested in taking their research a step further and testing the tug-of-war prediction for two-electron quantum dots, Zutic says.

Zutic adds that learning more about magnetism is important as society continues to find novel uses for magnets, which could advance technologies including lasers, medical imaging devices and, importantly, computers.

He explains the promise of magnet- or spin-based computing technology -- called "spintronics" -- by contrasting it with conventional electronics. Modern, electronic gadgets record and read data as a blueprint of ones and zeros that are represented, in circuits, by the presence or absence of electrons. Processing information requires moving electrons, which consumes energy and produces heat.

Spintronic gadgets, in contrast, store and process data by exploiting electrons' "up" and "down" spins, which can stand for the ones and zeros devices read. Future energy-saving improvements in data processing could include devices that process information by "flipping" spin instead of shuttling electrons around.

Studying how magnetism works on a small scale is particularly important, Zutic says, because "we would like to pack more information into less space."

And, of course, unraveling the mysteries of magnetism is satisfying for other, simpler reasons.

"Magnets have been fascinating people for thousands of years," Zutic says. "Some of this fascination was not always related to how you can make a better compass or a better computer hard drive. It was just peculiar that you have materials that attract one another, and you wanted to know why."

Zutic's research on magnetism is funded by the Department of Energy, Office of Naval Research, Air Force Office of Scientific Research and the National Science Foundation.

####

About University of Buffalo
The University at Buffalo is a premier research-intensive public university, a flagship institution in the State University of New York system and its largest and most comprehensive campus. UB's more than 28,000 students pursue their academic interests through more than 300 undergraduate, graduate and professional degree programs. Founded in 1846, the University at Buffalo is a member of the Association of American Universities.

For more information, please click here

Contacts:
Charlotte Hsu

716-645-4655

Copyright © University of Buffalo

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Govt.-Legislation/Regulation/Funding/Policy

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Nanoscale Trojan horses treat inflammation May 24th, 2016

Spintronics

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Spin lifetime anisotropy of graphene is much weaker than previously reported May 10th, 2016

Spintronics for future information technologies: Spin currents in topological insulators controlled May 2nd, 2016

Atomic magnets using hydrogen and graphene April 27th, 2016

Discoveries

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Announcements

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Gigantic ultrafast spin currents: Scientists from TU Wien (Vienna) are proposing a new method for creating extremely strong spin currents. They are essential for spintronics, a technology that could replace today's electronics May 25th, 2016

Diamonds closer to becoming ideal semiconductors: Researchers find new method for doping single crystals of diamond May 25th, 2016

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

Military

Nanoscale Trojan horses treat inflammation May 24th, 2016

Programmable materials find strength in molecular repetition May 23rd, 2016

Rice de-icer gains anti-icing properties: Dual-function, graphene-based material good for aircraft, extreme environments May 23rd, 2016

UW researchers unleash graphene 'tiger' for more efficient optoelectronics May 16th, 2016

Quantum Dots/Rods

Supercrystals with new architecture can enhance drug synthesis May 24th, 2016

ORNL demonstrates large-scale technique to produce quantum dots May 21st, 2016

First single-enzyme method to produce quantum dots revealed: Biological manufacturing process, pioneered by three Lehigh University engineers, produces equivalent quantum dots to those made chemically--but in a much greener, cheaper way May 9th, 2016

Superfast light source made from artificial atom April 28th, 2016

Research partnerships

Revealing the nature of magnetic interactions in manganese oxide: New technique for probing local magnetic interactions confirms 'superexchange' model that explains how the material gets its long-range magnetic order May 25th, 2016

Light can 'heal' defects in new solar cell materials: Defects in some new electronic materials can be removed by making ions move under illumination May 24th, 2016

Mille-feuille-filter removes viruses from water May 19th, 2016

Carnegie Mellon develops bio-mimicry method for preparing and labeling stem cells: Method allows researchers to prepare mesenchymal stem cells and monitor them using MRI May 19th, 2016

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







Car Brands
Buy website traffic