Third State Of Magnetism Discovered By MIT Researchers

December 21, 2012
Image Caption: 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. Image: Tianheng Han

redOrbit Staff & Wire Reports – Your Universe Online

While experts had previously only confirmed the existence of two states of magnetism, experts from the Massachusetts Institute of Technology (MIT) report that they have been able to experimentally demonstrate the existence of a third kind.

The MIT researchers have dubbed the new state a quantum spin liquid (QSL), and they describe their findings in this week’s edition of the journal Nature. It joins ferromagnetism (the simple form of magnetism featured in bar magnets and compass needles) and antiferromagentism (a more complex type of magnetism that occurs within solids and serves as the basis for read heads in computer hard drives).

In a recent statement, MIT physics professor Young Lee, senior author of the study, said that their work demonstrates that “there is a third fundamental state for magnetism.”

That third type, QSL, exists as a solid crystal but has a magnetic state that is described as liquid, the institute explained, and unlike the other types of magnetism, it undergoes frequent fluctuation of the magnetic orientations of its individual particles.

Lee explained that there is no static order to the magnetic orientations within the material, but that there is “a strong interaction” between those so-called magnetic moments, and they do not lock in place as a result of quantum effects. While he says that it is exceptionally hard to measure and/or prove the existence of the QSL state, the professor called their research “one of the strongest experimental data sets” attempting to do so.

The concept of this third magnetic state was first proposed by theorist Phillip Anderson in 1987, and since then Lee says that physicists have been working to prove its existence. The material itself that demonstrates the concept is a crystal of a mineral known as herbertsmithite. MIT said, that was only completed last year following approximately 10 months worth of work.

Since then, Lee and his colleagues have been hard at work, analyzing its properties.

“Through its experiments, the team made a significant discovery,” the institute said. “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’.”

They measured the state using a neutron spectrometer at the Maryland-based National Institute of Standards and Technology (NIST). By performing a technique known as neutron scattering, Lee and his colleagues discovered strong evidence of the spin state fractionalization, which he notes is “a fundamental theoretical prediction for spin liquids that we are seeing in a clear and detailed way for the first time.”

Their work could eventually lead to the development of improved data storage or communications, or the development of high-temperature superconductors. However, Lee warns that it could take a considerable amount of time to practically apply their findings. “We have to get a more comprehensive understanding of the big picture,” the MIT researcher said. “There is no theory that describes everything that we´re seeing.”

Source: redOrbit Staff & Wire Reports - Your Universe Online

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