Feeds

MIT boffins demonstrate NEW form of magnetism

Atom can't tell up from down in 'quantum spin liquid'

Intelligent flash storage arrays

A state of magnetism predicted in 1987 has been observed for the first time at MIT, with researchers saying that it might one day find applications in storage and communications technologies.

The “one day” is still quite some way off, however, with the researchers only at the very beginning of observing the properties of what’s called a “quantum spin liquid” (QSL).

The properties of a quantum spin liquid are revealed in the spin properties of atoms in a crystal. Rather than settling into a stable state, as happens in ferromagnetic and antiferromagnetic materials, the “spin moment” in a QSL is constantly changing.

MIT Herbertsmithite

MIT's Herbertsmithite crystal

In the familiar compass needle, magnetism comes from the alignment of all spins in the same direction. The second magnetic state, antiferromagnetism, was first proposed in the 1930s. In an antiferromagnetic material, the spin states align in such a way that the overall magnetism is zero, unless energy is applied. This property is exploited in hard drive read heads.

In the new state of magnetism, the magnetic orientation of particles is unable to settle into an ordered state. Instead, they fluctuate constantly, driven by quantum interactions between particles.

QSL only exists in a type of crystal called a kagome lattice. In the material examined in the MIT research, Herbertsmithite (named after its discoverer), copper atoms lie at the corners of triangular structures. Two of the copper atoms are able to align their spins in an “up-down” arrangement – but the third copper atom can’t align with both the others, so it flips between up and down.

Neutron scattering in Herbertsmithite

The blue regions in the NIST scan of Herbertsmithite show magnetically ordered regions. The green regions are exciting: they're where the spin state is disordered. Image: NIST

To actually observe the QSL, the researchers spent years manufacturing high-purity Herbertsmithite. The test sample was then imaged using the Multi-Axis Crystal Spetrometer (MACS) at the NIST Center for Neutron Research.

In a disordered material, neutrons scatter evenly across the sample. In the QSL sample, some regions scatter neutrons in a way consistent with magnetism – but in other regions the scattering appears disordered (those regions where the atom’s spin fails to settle down).

Wait, there’s more

Along the way, the researchers made another possible discovery as significant as the QSL: they believe they’ve observed fractionalised quantum states.

Quantum states are generally assumed to exist only as whole numbers – after all, the basis of quantum physics is that the quantum is the smallest possible change in state that can exist.

The MIT researchers say that their material exhibits a state with fractionalised excitations: “spinons” whose excited states apparently exist in a contiuum between quantum states. In the MIT release, the researches say observing this “highly controversial idea” is “a remarkable first”.

The research, conducted by professor Young Lee, Tianheng Han (lead author of the paper), and collaborators from MIT, NIST, Maryland University and Johns Hopkins University, is published in Nature (abstract here). ®

Intelligent flash storage arrays

More from The Register

next story
MARS NEEDS WOMEN, claims NASA pseudo 'naut: They eat less
'Some might find this idea offensive' boffin admits
Boffins who stare at goats: I do believe they’re SHRINKING
Alpine chamois being squashed by global warming
LOHAN crash lands on CNN
Overflies Die Welt en route to lively US news vid
Comet Siding Spring revealed as flying molehill
Hiding from this space pimple isn't going to do humanity's reputation any good
Experts brand LOHAN's squeaky-clean box
Phytosanitary treatment renders Vulture 2 crate fit for export
No sail: NASA spikes Sunjammer
'Solar sail' demonstrator project binned
Carry On Cosmonaut: Willful Child is a poor taste Star Trek parody
Cringeworthy, crude and crass jokes abound in Steven Erikson’s sci-fi debut
prev story

Whitepapers

Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
A strategic approach to identity relationship management
ForgeRock commissioned Forrester to evaluate companies’ IAM practices and requirements when it comes to customer-facing scenarios versus employee-facing ones.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.