Featured Research

from universities, journals, and other organizations

How Electrons 'Gain Weight' In Metal Compounds Near Absolute Zero

Date:
November 5, 2007
Source:
Rutgers University
Summary:
Physicists have performed computer simulations that show how electrons become one thousand times more massive in certain metal compounds when cooled to temperatures near absolute zero. The models may provide new clues as to how superconductivity works and how new superconducting materials could be fabricated. The researchers describe how electrons interact with other particles in these compounds to morph into a fluid of "heavy quasiparticles" or a "heavy fermion fluid."

A molecular model of the material studied by Rutgers physicists. In this representation of the crystal structure of CeIrIn5, the red, gold and gray spheres correspond to cerium, iridium and indium.
Credit: Rutgers University

Rutgers University physicists have performed computer simulations that show how electrons become one thousand times more massive in certain metal compounds when cooled to temperatures near absolute zero -- the point where all motion ceases. The models may provide new clues as to how superconductivity works and how new superconducting materials could be fabricated.

In a paper posted to Science Express, a Web site of research reports slated for upcoming print editions of Science, the researchers describe how electrons interact with other particles in these compounds to morph into what physicists call a fluid of "heavy quasiparticles" or a "heavy fermion fluid." While this effect has been previously observed in some materials, the Rutgers work employs new materials to provide a level of detail that has eluded scientists so far.

"In this paper, we essentially track the fate of electrons as we lower the temperature," said Gabi Kotliar, Board of Governors Professor of Physics in the School of Arts and Sciences. "Experimental physicists may have seen different aspects of this behavior, or they may have seen behaviors they did not understand. Our calculations reconcile what they've seen."

The Rutgers researchers based their models on experiments using a new metallic crystalline compound made of the elements cerium, indium and iridium. This and similar compounds that substitute cobalt and rhodium for iridium are excellent test beds for observing heavy electron behavior.

Earlier investigations used high-temperature superconducting materials called cuprates, which failed to give physicists a clear view of electron behavior because of disorders in the crystalline structure caused by doping. The new cerium-based compounds are simpler to study because they are free of dopants.

"The new compounds are for us what fruit flies are for genetics researchers," said Kristjan Haule, assistant professor of physics and astronomy. "Fruit flies are easy to breed and have a simple gene makeup that's easy to change. Likewise, these compounds are easy to make, structurally straightforward and adjustable, giving us a clearer view into the many properties of matter that arise at low temperatures. For example, we can use a magnetic field to kill superconductivity and examine the state of matter from which superconductivity arose."

These compounds are examples of strongly correlated materials, or materials with strongly interacting electrons, that can't be described by theories that treat electrons as largely independent entities. The terms "heavy quasiparticles" refers to how electrons interact with each other and, as a result of those interactions, form a new type of particle called a "quasiparticle."

In explaining how this effect appears at low temperatures and vanishes at higher ones, Haule noted that electrons in f-orbitals are tightly bound to cerium atoms at room temperature. But as the temperature drops, the electrons exhibit coherent behavior, or delocalization from their atoms. At 50 degrees above absolute zero, or 50 degrees Kelvin, the researchers clearly observe quasiparticles as electrons interact with each other and other electrons in the metal known as conduction electrons.

The work done by Haule and his colleagues is in a branch of physics known as condensed matter physics, which deals with the physical properties of solid and liquid matter. Their models of heavy quasiparticles draw from Haule's earlier work merging two theories of atomic modeling, known as local density approximation and dynamical mean field theory, or LDA+DMFT.

Collaborating with Haule and Kotliar was Ji-Hoon Shim, a postdoctoral fellow. The National Science Foundation's Division of Materials Research and the Rutgers Center for Materials Theory supported their research. Shim received postdoctoral research funding from the Korean Research Foundation.


Story Source:

The above story is based on materials provided by Rutgers University. Note: Materials may be edited for content and length.


Cite This Page:

Rutgers University. "How Electrons 'Gain Weight' In Metal Compounds Near Absolute Zero." ScienceDaily. ScienceDaily, 5 November 2007. <www.sciencedaily.com/releases/2007/11/071101144954.htm>.
Rutgers University. (2007, November 5). How Electrons 'Gain Weight' In Metal Compounds Near Absolute Zero. ScienceDaily. Retrieved September 21, 2014 from www.sciencedaily.com/releases/2007/11/071101144954.htm
Rutgers University. "How Electrons 'Gain Weight' In Metal Compounds Near Absolute Zero." ScienceDaily. www.sciencedaily.com/releases/2007/11/071101144954.htm (accessed September 21, 2014).

Share This



More Matter & Energy News

Sunday, September 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thousands March in NYC Over Climate Change

Thousands March in NYC Over Climate Change

AP (Sep. 21, 2014) — Accompanied by drumbeats, wearing costumes and carrying signs, thousands of demonstrators filled the streets of Manhattan and other cities around the world on Sunday to urge policy makers to take action on climate change. (Sept. 21) Video provided by AP
Powered by NewsLook.com
What This MIT Sensor Could Mean For The Future Of Robotics

What This MIT Sensor Could Mean For The Future Of Robotics

Newsy (Sep. 20, 2014) — MIT researchers developed a light-based sensor that gives robots 100 times the sensitivity of a human finger, allowing for "unprecedented dexterity." Video provided by Newsy
Powered by NewsLook.com
MIT BioSuit A New Take On Traditional Spacesuits

MIT BioSuit A New Take On Traditional Spacesuits

Newsy (Sep. 19, 2014) — The MIT BioSuit could be an alternative to big, bulky traditional spacesuits, but the concept needs some work. Video provided by Newsy
Powered by NewsLook.com
New Music With Recycled Instruments at Colombia Fest

New Music With Recycled Instruments at Colombia Fest

AFP (Sep. 19, 2014) — Jars, bottles, caps and even a pizza box, recovered from the trash, were the elements used by four musical groups at the "RSFEST2014 Sonorities Recycling Festival", in Colombian city of Cali. Duration: 00:49 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins