Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Physicists observe magnetism in gas for the first time

06.10.2009
An international team of physicists has for the first time observed magnetic behaviour in an atomic gas, addressing a decades-old debate as to whether it is possible for a gas or liquid to become ferromagnetic and exhibit magnetic properties.

“Magnets are all around us – holding postcards on the refrigerator, pointing to magnetic north on a compass, and in speakers and headphones – yet some mysteries remain,” says Joseph H. Thywissen, a professor of physics at the University of Toronto and a visiting member of the Massachusetts Institute of Technology-based team leading the research. “We have perhaps found the simplest situation in which permanent magnetism can exist."

The scientists observed the behaviour in a gas of lithium atoms trapped in the focus of an infrared laser beam. The gas was cooled to 150 nK, less than a millionth of a degree above absolute zero, which is at -273 C. When repulsive forces between the atoms were gradually increased, several features indicated that the gas had become ferromagnetic. The cloud first became bigger and then suddenly shrunk, and when the atoms were released from the trap, they suddenly expanded faster. These observations were reported in the 18 Sept 2009 issue of Science, in a paper titled “Itinerant Ferromagnetism in a Fermi Gas of Ultracold Atoms”.

This and other observations agreed with theoretical predictions for a transition to a ferromagnetic state. Ferromagnetic materials are those that, below a specific temperature, become magnetized even in the absence of a strong magnetic field. In common magnets, such as iron and nickel that consist of a repeating crystal structure, ferromagnetism occurs when unpaired electrons within the material spontaneously align in the same direction.

“Magnetism only occurs in a strongly interacting regime, where calculations – even using today’s fastest computers – are difficult,” says Thywissen. “Since naturally occurring gases do not have strong enough interactions to address the question, we turned to ultra-cold gases for answers.”

If confirmed, these results may enter textbooks on magnetism, showing that a gas of fermions does not need a crystalline structure to exhibit magnetic properties. “The evidence is pretty strong, but it is not yet a slam dunk,” says MIT physics professor and co-principal investigator David E. Pritchard. “We were not able to observe regions where the atoms all point in the same direction. They started to form molecules and may not have had enough time to align themselves.”

Thywissen's interest in the topic of ultra-cold ferromagnetism originated in theoretical work at Toronto led by Professor Arun Paramekanti in the physics department, along with graduate student Lindsay LeBlanc. "We assumed that ferromagnetism did exist for a gas, and then asked what its properties would be," explains LeBlanc. "Surprisingly, we found there were simple energetic signatures of ferromagnetism – that were eventually observed at MIT."

At MIT, the team was led by principal investigator Wolfgang Ketterle, and included graduate students Gyu-Boong Jo, Ye-Ryoung Lee and Caleb A. Christensen, post-doctoral associate Jae-Hoon Choi, and undergraduate student Tony H. Kim. Thywissen is affiliated with the University of Toronto’s Centre of Quantum Information and Quantum Control, and is a Senior Fellow at Massey College.

Canadian funding agencies include the National Science and Engineering Research Council (NSERC) and the Canadian Institute for Advanced Research (CIfAR). US funding included the National Science Foundation, the Office of Naval Research, through a Multidisciplinary University Research Initiative (MURI) program, and by the Army Research Office with funds from the Defense Advanced Research Projects Agency (DARPA) Optical Lattice Emulator (OLE) program.

MEDIA CONTACTS:

Sean Bettam
Communications, Faculty of Arts & Science
University of Toronto
416-946-7950
s.bettam@utoronto.ca

Sean Bettam | EurekAlert!
Further information:
http://www.utoronto.ca

More articles from Physics and Astronomy:

nachricht Astronomers release most complete ultraviolet-light survey of nearby galaxies
18.05.2018 | NASA/Goddard Space Flight Center

nachricht A quantum entanglement between two physically separated ultra-cold atomic clouds
17.05.2018 | University of the Basque Country

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: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>