New kind of magnetism discovered: ’Quantum Spin Liquid’
2012 12 24

From: ScienceDaily.com

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."


[...]

Read the full article at: sciencedaily.com











Related Articles
Cooking With a Magnetic Field?
Earth’s Magnetic Field Made Quick Flip- Flop
Magnets kill cancer cells in lab
Scientist Finds Hidden Portals in Earth’s Magnetic Field
Moon Oddly Magnetic—Giant Asteroid Crash to Blame?
Quantum Entanglement Leaps Beyond Einstein --"New States of Light"
Birds use quantum theory to literally ’see’ Earth’s magnetic field as they fly
For newly discovered ’quantum spin liquid’, the beauty is in its simplicity
Scientists produce a crystal that could help unlock the mystery of high-temperature superconductors


Latest News from our Front Page

Left and their big fat multi-cultural lie
2014 08 30
Picture the scene; a taxi is pulled over by an officer from South Yorkshire Police who finds a half-naked 12-year-old in the back of the cab so drunk or drugged that she can hardly stand. When interviewed, the taxi driver is found to have pornographic pictures of the girl on his phone. The officer hands back the phone and – no ...
Rotherham - Child sacrifice to diversity god
2014 08 30
It is sad to see how the once great nation of England has fallen. Britain now rivals North Korea for totalitarian control. If you are White, the wrong word can send you to jail. If you are non-White you are free to rape and kill the native British with impunity. If Henry the VIII came back from the grave, he could ...
Hungary’s Orban Bashes Liberal Immigration Policy
2014 08 29
Hungary’s Prime Minister Viktor Orban on Monday lashed out against immigration, setting one of the main policy objectives of his next term in power after winning parliamentary elections in April. “The goal is to cease immigration whatsoever,” said Hungary’s prime minister. “I think the current liberal immigration policy, which is considered obvious and morally based, is hypocrite,” Mr. Orban said. At a ...
China’s “Duplitecture” Cities Mimic the World’s Greatest Architectural Hits
2014 08 29
The best knockoffs in the world are in China. There are plenty of fake designer handbags and Rolexes, but China’s knockoffs go way beyond fashion. There are knockoff Apple stores that look so much like the real thing that some employees believe they are working in real Apple stores. And then there are entire knockoff cities. There are Venices with ...
Kiev loses control of Novoazovsk, rebel troops advance in southeast Ukraine
2014 08 29
Kiev’s troops had to leave the eastern Ukrainian city of Novoazovsk to save their lives, said the country’s Security and Defense Council. The authorities admitted that self-defense forces are advancing and leading a counteroffensive in the southeast. Along with Novoazovsk, Kiev troops have lost control over the villages of Amvrosiivka and Starobeshevo in the Donetsk Region of Eastern Ukraine. According to Ukraine’s ...
More News »