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.
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.
MIT physicists grew this pure crystal of herbertsmithite in their laboratory. This sample, which took 10 months to grow, is 7 mm long (just over a quarter-inch) and weighs 0.2 grams.
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.
Finding the evidence
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.
Although it is extremely difficult to measure, or prove the existence, of this exotic state, Lee says, "this is one of the strongest experimental data sets out there that [does] this. What used to just be in theorists’ models is a real physical system."
Philip Anderson, a leading theorist, first proposed the concept in 1987, saying that this state could be relevant to high-temperature superconductors, Lee says. "Ever since then, physicists have wanted to make such a state," he adds. "It’s only in the past few years that we’ve made progress."
The material itself is a crystal of a mineral called herbertsmithite. Lee and his colleagues first succeeded in making a large, pure crystal of this material last year -- a process that took 10 months -- and have since been studying its properties in detail.
"This was a multidisciplinary collaboration, with physicists and chemists," Lee explains. "You need both … to synthesize the material and study it with advanced physics techniques. Theorists were also crucial to this."
Through its experiments, the team made a significant discovery, Lee says: They found a state with fractionalized excitations, which had been predicted by some theorists but was a highly controversial idea. While most matter has discrete quantum states whose changes are expressed as whole numbers, this QSL material exhibits fractional quantum states. In fact, the researchers found that these excited states, called spinons, form a continuum. This observation, they say in their Nature paper, is "a remarkable first."
ISIS to France: "We will be coming. Victory has been promised to us by Allah" 2015-11-26 3:33
Homegrown French ISIS fighters have issued a chilling threat of new attacks on France just 24 hours after the terrorist group used movie footage of the Eiffel Tower's collapse in another video.
A balaclava-clad militant is seen warning 'we will be coming, we will come to crush your country' in footage posted on Twitter earlier today.
It is unclear where the film ...
ISIS teenage 'poster girl' Samra Kesinovic 'beaten to death' as she tried to flee the group 2015-11-26 1:07 She appeared in social media images for the group carrying a Kalashnikov and surrounded by armed men
A teenage girl who ran away from her Vienna home to join Isis in Syria has reportedly been beaten to death by the group after trying to escape.
Samra Kesinovic, 17, travelled to Syria last year with her friend Sabina Selimovic, 15.
The two became a ...
The Right Stuff's flagship podcast "The Daily Shoah" has been censored by Soundcloud 2015-11-25 22:56
Editor's note: The PC corporate moral police strike again. Just as Radio 3Fourteen & Red Ice Radio were censored from iTunes, The Daily Shoah was pulled from Soundcloud today. As per usual, there is a double standard, they allow any kind of anti-White material:
No counter culture humor making fun of the genocidal mainstream garbage is allowed!
Soundcloud took it upon ...
Merkel Welcomes A Million More: Vows To Stand By Refugee Policy Despite Security Fears 2015-11-25 21:05
Chancellor Angela Merkel vowed on Wednesday to stick to her open-door refugee policy, defying criticism at home and abroad which has intensified due to growing fears about a potential security risk after the Islamist attacks in Paris.
Conservative Merkel faces splits in her right-left coalition and pressure from EU states, including France, over her insistence that Germany can cope with up ...
Paris Terrorist Was Gay 'Rent Boy', On The Run From Islamic State And Police 2015-11-25 20:16
The elusive eighth Paris attacker and one of three brothers implicated in the atrocity reportedly frequented gay clubs before the attack. He may have backed out of his mission at the last minute, and is possibly on the run from Islamic State as well as authorities.
â€œWe had him down as a rent boy, he was always hanging out with that ...