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."
New York Times Publishes Darren Wilson’s Street Address and Photo of House #Ferguson 2014 11 26 Hey here are the two @nytimes scumbags that published Wilson’s home address. —> @juliebosman & @campbellnyt— Ben Howe (@BenHowe) November 25, 2014
Michael Brown’s Stepdad Shouting ‘Burn This Bitch Down’
The New York Times published information about the address of Ferguson Police Officer Darren Wilson on Monday in a move that has generated controversy. Tensions are running high in Ferguson, Missouri, as ...
How Monsanto is Destroying the Brains and Health of Everyone 2014 11 25 Interested in slowing your aging process? Take note!
One of my most recent blog entries summarized roughly 10 years of research related to the consequences of inflammatory processes in the periphery of the body, such as the gut, and how this was driving brain degenerative inflammatory processes within the brain.
One of the key findings from that research was how pathogenic ...
Guccifer: Pennsylvania City to be Nuked Next Year 2014 11 25
From Youtube: Renowned hacker Guccifer, who accessed the private emails of numerous top military, political and intelligence leaders, told the New York Times that a city in Pennsylvania is the target of a nuke attack in 2015. Guccifer also revealed that he is sitting on an archive of hacked emails that have not been publicly released.
The New Normal: Artist Butchers "Disney Princesses" with Breast Cancer Scars 2014 11 25 Comment: Natural remedies for cancer, like: diet, vitamins, minerals and other supplements are NEVER addressed. Neither are chemicals and wi-fi saturated environment recognized for the rise in these new epidemics. Instead ... what do they do? They normalize it. Like it’s just the new thing you need to do. Change nothing and adapt to these new circumstances of mutilation kids. ...