New kind of magnetism discovered: Experiments demonstrate 'quantum spin liquid'

[unhappycamper]

http://phys.org/news/2012-12-kind-magnetism-quantum-liquid.html



Following up on earlier theoretical predictions, MIT researchers have now demonstrated experimentally the existence of a fundamentally new kind of magnetic behavior, adding to the two previously known states of magnetism.

New kind of magnetism discovered: Experiments demonstrate 'quantum spin liquid'
December 20, 2012
by David Chandler

Ferromagnetism—the simple magnetism of a bar magnet or compass needle—has been known for centuries. In a second type of magnetism, antiferromagnetism, the magnetic fields of the ions within a metal or alloy cancel each other out. In both cases, the materials become magnetic only when cooled below a certain critical temperature. The prediction and discovery of antiferromagnetism—the basis for the read heads in today's computer hard disks—won Nobel Prizes in physics for Louis Neel in 1970 and for MIT professor emeritus Clifford Shull in 1994.

"We're showing that there is a third fundamental state for magnetism," says MIT professor of physics Young Lee. The experimental work showing the existence of this new state, called a quantum spin liquid (QSL), is reported this week in the journal Nature, with Lee as the senior author and Tianheng Han, who earned his PhD in physics at MIT earlier this year, as lead author.

The QSL is a solid crystal, but its magnetic state is described as liquid: Unlike the other two kinds of magnetism, the magnetic orientations of the individual particles within it fluctuate constantly, resembling the constant motion of molecules within a true liquid.

There is no static order to the magnetic orientations, known as magnetic moments, within the material, Lee explains. "But there is a strong interaction between them, and due to quantum effects, they don't lock in place," he says.

[AldoLeopold]

1. I love major new discoveries like this

It shows we still have so much to learn about the universe. I think many of us graduate with science degrees and assume we have the bottom line on a lot of subjects - but its always changing. Science is so exciting to me