Physicists observe magnetism in gas for the first time

Toronto, October 3 (ANI): 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," said 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," he added.

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 Celsius.

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.

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," said Thywissen.

"Since naturally occurring gases do not have strong enough interactions to address the question, we turned to ultra-cold gases for answers," he added.

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. (ANI)